Understanding statistics.
Understanding statistical data.
The bottom line.
Katrina Ávila Munichiello is an experienced editor, writer, fact-checker, and proofreader with more than fourteen years of experience working with print and online publications.
Statistics is a branch of applied mathematics that involves the collection, description, analysis, and inference of conclusions from quantitative data. The mathematical theories behind statistics rely heavily on differential and integral calculus, linear algebra, and probability theory.
People who do statistics are referred to as statisticians. They’re particularly concerned with determining how to draw reliable conclusions about large groups and general events from the behavior and other observable characteristics of small samples. These small samples represent a portion of the large group or a limited number of instances of a general phenomenon.
Dennis Madamba / Investopedia
Statistics are used in virtually all scientific disciplines, such as the physical and social sciences as well as in business, medicine, the humanities, government, and manufacturing. Statistics is fundamentally a branch of applied mathematics that developed from the application of mathematical tools, including calculus and linear algebra, to probability theory.
In practice, statistics is the idea that we can learn about the properties of large sets of objects or events (a population ) by studying the characteristics of a smaller number of similar objects or events (a sample ). Gathering comprehensive data about an entire population is too costly, difficult, or impossible in many cases, so statistics start with a sample that can be conveniently or affordably observed.
Statisticians measure and gather data about the individuals or elements of a sample and analyze this data to generate descriptive statistics. They can then use these observed characteristics of the sample data, which are properly called “statistics,” to make inferences or educated guesses about the unmeasured characteristics of the broader population, known as the parameters.
Statistics informally dates back centuries. An early record of correspondence between French mathematicians Pierre de Fermat and Blaise Pascal in 1654 is often cited as an early example of statistical probability analysis.
The two major areas of statistics are known as descriptive statistics , which describes the properties of sample and population data, and inferential statistics, which uses those properties to test hypotheses and draw conclusions. Descriptive statistics include mean (average), variance, skewness , and kurtosis . Inferential statistics include linear regression analysis, analysis of variance (ANOVA), logit/Probit models, and null hypothesis testing.
Descriptive statistics mostly focus on the central tendency, variability, and distribution of sample data. Central tendency means the estimate of the characteristics, a typical element of a sample or population. It includes descriptive statistics such as mean , median , and mode .
Variability refers to a set of statistics that show how much difference there is among the elements of a sample or population along the characteristics measured. It includes metrics such as range, variance , and standard deviation .
The distribution refers to the overall “shape” of the data, which can be depicted on a chart such as a histogram or a dot plot, and includes properties such as the probability distribution function, skewness, and kurtosis. Descriptive statistics can also describe differences between observed characteristics of the elements of a data set. They can help us understand the collective properties of the elements of a data sample and form the basis for testing hypotheses and making predictions using inferential statistics.
Inferential statistics is a tool that statisticians use to draw conclusions about the characteristics of a population, drawn from the characteristics of a sample. It is also used to determine how certain they can be of the reliability of those conclusions. Based on the sample size and distribution, statisticians can calculate the probability that statistics, which measure the central tendency, variability, distribution, and relationships between characteristics within a data sample, provide an accurate picture of the corresponding parameters of the whole population from which the sample is drawn.
Inferential statistics are used to make generalizations about large groups, such as estimating average demand for a product by surveying the buying habits of a sample of consumers or attempting to predict future events. This might mean projecting the future return of a security or asset class based on returns in a sample period.
Regression analysis is a widely used technique of statistical inference. It is used to determine the strength and nature of the relationship (the correlation) between a dependent variable and one or more explanatory (independent) variables. The output of a regression model is often analyzed for statistical significance, meaning that a result from findings generated by testing or experimentation is not likely to have occurred randomly or by chance. In other words, statistical significance suggests the results are attributable to a specific cause elucidated by the data.
Having statistical significance is important for academic disciplines or practitioners that rely heavily on analyzing data and research.
The terms “mean,” “median,” and “mode” fall under the umbrella of central tendency. They describe an element that’s typical in a given sample group. You can find the mean descriptor by adding the numbers in the group and dividing the result by the number of data set observations.
The middle number in the set is the median. Half of all included numbers are higher than the median, and half are lower. The median home value in a neighborhood would be $350,000 if five homes were located there and valued at $500,000, $400,000, $350,000, $325,000, and $300,000. Two values are higher, and two are lower.
Mode identifies the number that falls between the highest and lowest values. It appears most frequently in the data set.
The root of statistics is driven by variables. A variable is a data set that can be counted that marks a characteristic or attribute of an item. For example, a car can have variables such as make, model, year, mileage, color, or condition. By combining the variables across a set of data, such as the colors of all cars in a given parking lot, statistics allows us to better understand trends and outcomes.
There are two main types of variables:
First, qualitative variables are specific attributes that are often non-numeric. Many of the examples given in the car example are qualitative. Other examples of qualitative variables in statistics are gender, eye color, or city of birth. Qualitative data is most often used to determine what percentage of an outcome occurs for any given qualitative variable. Qualitative analysis often does not rely on numbers. For example, trying to determine what percentage of women own a business analyzes qualitative data.
The second type of variable in statistics is quantitative variables. Quantitative variables are studied numerically and only have weight when they’re about a non-numerical descriptor. Similar to quantitative analysis, this information is rooted in numbers. In the car example above, the mileage driven is a quantitative variable, but the number 60,000 holds no value unless it is understood that it is the total number of miles driven.
Quantitative variables can be further broken into two categories. First, discrete variables have limitations in statistics and infer that there are gaps between potential discrete variable values. The number of points scored in a football game is a discrete variable because:
Statistics also makes use of continuous quantitative variables. These values run along a scale. Discrete values have limitations, but continuous variables are often measured into decimals. Any value within possible limits can be obtained when measuring the height of the football players, and the heights can be measured down to 1/16th of an inch, if not further.
Statisticians can hold various titles and positions within a company. The average total compensation for a statistician with one to three years of experience was $81,885 as of December 2023. This increased to $109,288 with 15 years of experience.
There are several resulting levels of measurement after analyzing variables and outcomes. Statistics can quantify outcomes in four ways.
There’s no numerical or quantitative value, and qualities are not ranked. Nominal-level measurements are instead simply labels or categories assigned to other variables. It’s easiest to think of nominal-level measurements as non-numerical facts about a variable.
Example : The name of the U.S. president elected in 2020 was Joseph Robinette Biden Jr.
Outcomes can be arranged in an order, but all data values have the same value or weight. Although they’re numerical, ordinal-level measurements can’t be subtracted against each other in statistics because only the position of the data point matters. Ordinal levels are often incorporated into nonparametric statistics and compared against the total variable group.
Example : American Fred Kerley was the second-fastest man at the 2020 Tokyo Olympics based on 100-meter sprint times.
Outcomes can be arranged in order, but differences between data values may now have meaning. Two data points are often used to compare the passing of time or changing conditions within a data set. There is often no “starting point” for the range of data values, and calendar dates or temperatures may not have a meaningful intrinsic zero value.
Example : Inflation hit 8.6% in May 2022. The last time inflation was that high was in December 1981 .
Outcomes can be arranged in order, and differences between data values now have meaning. But there’s a starting point or “zero value” that can be used to further provide value to a statistical value. The ratio between data values has meaning, including its distance away from zero.
Example : The lowest meteorological temperature recorded was -128.6 degrees Fahrenheit in Antarctica in 1983.
Often, it's not possible to gather data from every data point within a population to gather statistical information. Statistics relies instead on different sampling techniques to create a representative subset of the population that’s easier to analyze. In statistics, there are several primary types of sampling.
Simple random sampling calls for every member within the population to have an equal chance of being selected for analysis. The entire population is used as the basis for sampling, and any random generator based on chance can select the sample items. For example, 100 individuals are lined up and 10 are chosen at random.
Systematic sampling calls for a random sample as well, but its technique is slightly modified to make it easier to conduct. A single random number is generated to determine the starting point, and individuals are then selected at a specified regular interval until the sample size is complete. For example, if 100 individuals are lined up and numbered, and the random starting point is the seventh individual, every subsequent ninth individual (i.e., 7th, 16th, 25th, etc.) is selected until 10 sample items have been selected.
Stratified sampling calls for more control over your sample. The population is divided into subgroups based on similar characteristics. Then you calculate how many people from each subgroup would represent the entire population. For example, 100 individuals are grouped by gender and race. Then a sample from each subgroup is taken in proportion to how representative that subgroup is of the population.
Cluster sampling calls for subgroups as well, but each subgroup should be representative of the population. The entire subgroup is randomly selected instead of randomly selecting individuals within a subgroup.
Not sure which Major League Baseball player should have won Most Valuable Player last year? Statistics, often used to determine value, is often cited when the award for best player is announced. Statistics can include batting average, number of home runs hit, and stolen bases.
Statistics is prominent in finance, investing, business, and a wide scope of sectors. Much of the information you see and the data you’re given is derived from statistics, which are used in all facets of a business.
Statistics is used to conduct research, evaluate outcomes, develop critical thinking, and make informed decisions about a set of data. Statistics can be used to inquire about almost any field of study to investigate why things happen, when they occur, and whether reoccurrence is predictable.
Descriptive statistics are used to describe or summarize the characteristics of a sample or data set, such as a variable’s mean, standard deviation, or frequency. Inferential statistics employ any number of techniques to relate variables in a data set to one another. An example would be using correlation or regression analysis. These can then be used to estimate forecasts or infer causality.
Statistics are done whenever data are collected and analyzed and used widely across an array of applications and professions. These include government agencies, academic research, investment analysis, and many others.
Economists collect and look at all sorts of data ranging from consumer spending and housing starts to inflation and GDP growth. In finance, analysts and investors collect data about companies, industries, sentiment, and market data on price and volume. The use of inferential statistics in these fields is known as econometrics. Several important financial models, including the capital asset pricing model (CAPM) , modern portfolio theory (MPT) and the Black-Scholes options pricing model, rely on statistical inference.
Statistics is the practice of analyzing data and drawing inferences from the sample results. Across a variety of fields—from governmental agencies to finance—statistics is used to gather conclusions about a given data set.
The study of statistics can lead to a career as a statistician, but it can also be a handy metric in everyday life. When you’re analyzing the odds that your favorite team will win the Super Bowl before you place a bet, gauging the viability of an investment, or determining whether you’re being comparatively overcharged for a product or service, statistics can be used to gain insights on probable outcomes of objects or events.
Encyclopœdia Britannica. “ Probability and Statistics .”
Coursera. “ How Much Do Statisticians Make? Your 2024 Salary Guide .”
Olympics. “ Tokyo 2020: Athletics Men’s 100m Results .”
U.S. Bureau of Labor Statistics. “ Consumer Price Index .”
Arizona State University, World Meteorological Organization’s World Weather & Climate Extremes Archive. “ World: Lowest Temperature .”
Baseball Reference. “ MLB Most Valuable Player MVP Award Winners .”
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Published on 4 November 2022 by Pritha Bhandari . Revised on 9 January 2023.
Descriptive statistics summarise and organise characteristics of a data set. A data set is a collection of responses or observations from a sample or entire population .
In quantitative research , after collecting data, the first step of statistical analysis is to describe characteristics of the responses, such as the average of one variable (e.g., age), or the relation between two variables (e.g., age and creativity).
The next step is inferential statistics , which help you decide whether your data confirms or refutes your hypothesis and whether it is generalisable to a larger population.
Types of descriptive statistics, frequency distribution, measures of central tendency, measures of variability, univariate descriptive statistics, bivariate descriptive statistics, frequently asked questions.
There are 3 main types of descriptive statistics:
You can apply these to assess only one variable at a time, in univariate analysis, or to compare two or more, in bivariate and multivariate analysis.
A data set is made up of a distribution of values, or scores. In tables or graphs, you can summarise the frequency of every possible value of a variable in numbers or percentages.
Gender | Number |
---|---|
Male | 182 |
Female | 235 |
Other | 27 |
From this table, you can see that more women than men or people with another gender identity took part in the study. In a grouped frequency distribution, you can group numerical response values and add up the number of responses for each group. You can also convert each of these numbers to percentages.
Library visits in the past year | Percent |
---|---|
0–4 | 6% |
5–8 | 20% |
9–12 | 42% |
13–16 | 24% |
17+ | 8% |
Measures of central tendency estimate the center, or average, of a data set. The mean , median and mode are 3 ways of finding the average.
Here we will demonstrate how to calculate the mean, median, and mode using the first 6 responses of our survey.
The mean , or M , is the most commonly used method for finding the average.
To find the mean, simply add up all response values and divide the sum by the total number of responses. The total number of responses or observations is called N .
Data set | 15, 3, 12, 0, 24, 3 |
---|---|
Sum of all values | 15 + 3 + 12 + 0 + 24 + 3 = 57 |
Total number of responses | = 6 |
Mean | Divide the sum of values by to find : 57/6 = |
The median is the value that’s exactly in the middle of a data set.
To find the median, order each response value from the smallest to the biggest. Then, the median is the number in the middle. If there are two numbers in the middle, find their mean.
Ordered data set | 0, 3, 3, 12, 15, 24 |
---|---|
Middle numbers | 3, 12 |
Median | Find the mean of the two middle numbers: (3 + 12)/2 = |
The mode is the simply the most popular or most frequent response value. A data set can have no mode, one mode, or more than one mode.
To find the mode, order your data set from lowest to highest and find the response that occurs most frequently.
Ordered data set | 0, 3, 3, 12, 15, 24 |
---|---|
Mode | Find the most frequently occurring response: |
Measures of variability give you a sense of how spread out the response values are. The range, standard deviation and variance each reflect different aspects of spread.
The range gives you an idea of how far apart the most extreme response scores are. To find the range , simply subtract the lowest value from the highest value.
The standard deviation ( s ) is the average amount of variability in your dataset. It tells you, on average, how far each score lies from the mean. The larger the standard deviation, the more variable the data set is.
There are six steps for finding the standard deviation:
Raw data | Deviation from mean | Squared deviation |
---|---|---|
15 | 15 – 9.5 = 5.5 | 30.25 |
3 | 3 – 9.5 = -6.5 | 42.25 |
12 | 12 – 9.5 = 2.5 | 6.25 |
0 | 0 – 9.5 = -9.5 | 90.25 |
24 | 24 – 9.5 = 14.5 | 210.25 |
3 | 3 – 9.5 = -6.5 | 42.25 |
= 9.5 | Sum = 0 | Sum of squares = 421.5 |
Step 5: 421.5/5 = 84.3
Step 6: √84.3 = 9.18
The variance is the average of squared deviations from the mean. Variance reflects the degree of spread in the data set. The more spread the data, the larger the variance is in relation to the mean.
To find the variance, simply square the standard deviation. The symbol for variance is s 2 .
Univariate descriptive statistics focus on only one variable at a time. It’s important to examine data from each variable separately using multiple measures of distribution, central tendency and spread. Programs like SPSS and Excel can be used to easily calculate these.
Visits to the library | |
---|---|
6 | |
Mean | 9.5 |
Median | 7.5 |
Mode | 3 |
Standard deviation | 9.18 |
Variance | 84.3 |
Range | 24 |
If you were to only consider the mean as a measure of central tendency, your impression of the ‘middle’ of the data set can be skewed by outliers, unlike the median or mode.
Likewise, while the range is sensitive to extreme values, you should also consider the standard deviation and variance to get easily comparable measures of spread.
If you’ve collected data on more than one variable, you can use bivariate or multivariate descriptive statistics to explore whether there are relationships between them.
In bivariate analysis, you simultaneously study the frequency and variability of two variables to see if they vary together. You can also compare the central tendency of the two variables before performing further statistical tests .
Multivariate analysis is the same as bivariate analysis but with more than two variables.
In a contingency table, each cell represents the intersection of two variables. Usually, an independent variable (e.g., gender) appears along the vertical axis and a dependent one appears along the horizontal axis (e.g., activities). You read ‘across’ the table to see how the independent and dependent variables relate to each other.
Number of visits to the library in the past year | |||||
---|---|---|---|---|---|
Group | 0–4 | 5–8 | 9–12 | 13–16 | 17+ |
Children | 32 | 68 | 37 | 23 | 22 |
Adults | 36 | 48 | 43 | 83 | 25 |
Interpreting a contingency table is easier when the raw data is converted to percentages. Percentages make each row comparable to the other by making it seem as if each group had only 100 observations or participants. When creating a percentage-based contingency table, you add the N for each independent variable on the end.
Visits to the library in the past year (Percentages) | ||||||
---|---|---|---|---|---|---|
Group | 0–4 | 5–8 | 9–12 | 13–16 | 17+ | |
Children | 18% | 37% | 20% | 13% | 12% | 182 |
Adults | 15% | 20% | 18% | 35% | 11% | 235 |
From this table, it is more clear that similar proportions of children and adults go to the library over 17 times a year. Additionally, children most commonly went to the library between 5 and 8 times, while for adults, this number was between 13 and 16.
A scatter plot is a chart that shows you the relationship between two or three variables. It’s a visual representation of the strength of a relationship.
In a scatter plot, you plot one variable along the x-axis and another one along the y-axis. Each data point is represented by a point in the chart.
From your scatter plot, you see that as the number of movies seen at movie theaters increases, the number of visits to the library decreases. Based on your visual assessment of a possible linear relationship, you perform further tests of correlation and regression.
Descriptive statistics summarise the characteristics of a data set. Inferential statistics allow you to test a hypothesis or assess whether your data is generalisable to the broader population.
The 3 main types of descriptive statistics concern the frequency distribution, central tendency, and variability of a dataset.
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Random sampling and random assignment are fundamental concepts in the realm of research methods and statistics. However, many students struggle to differentiate between these two concepts, and very often use these terms interchangeably. Here we will explain the distinction between random sampling and random assignment.
Random sampling refers to the method you use to select individuals from the population to participate in your study. In other words, random sampling means that you are randomly selecting individuals from the population to participate in your study. This type of sampling is typically done to help ensure the representativeness of the sample (i.e., external validity). It is worth noting that a sample is only truly random if all individuals in the population have an equal probability of being selected to participate in the study. In practice, very few research studies use “true” random sampling because it is usually not feasible to ensure that all individuals in the population have an equal chance of being selected. For this reason, it is especially important to avoid using the term “random sample” if your study uses a nonprobability sampling method (such as convenience sampling).
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Random assignment refers to the method you use to place participants into groups in an experimental study. For example, say you are conducting a study comparing the blood pressure of patients after taking aspirin or a placebo. You have two groups of patients to compare: patients who will take aspirin (the experimental group) and patients who will take the placebo (the control group). Ideally, you would want to randomly assign the participants to be in the experimental group or the control group, meaning that each participant has an equal probability of being placed in the experimental or control group. This helps ensure that there are no systematic differences between the groups before the treatment (e.g., the aspirin or placebo) is given to the participants. Random assignment is a fundamental part of a “true” experiment because it helps ensure that any differences found between the groups are attributable to the treatment, rather than a confounding variable.
So, to summarize, random sampling refers to how you select individuals from the population to participate in your study. Random assignment refers to how you place those participants into groups (such as experimental vs. control). Knowing this distinction will help you clearly and accurately describe the methods you use to collect your data and conduct your study.
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Published on September 4, 2020 by Pritha Bhandari . Revised on June 22, 2023.
While descriptive statistics summarize the characteristics of a data set, inferential statistics help you come to conclusions and make predictions based on your data.
When you have collected data from a sample , you can use inferential statistics to understand the larger population from which the sample is taken.
Inferential statistics have two main uses:
Descriptive versus inferential statistics, estimating population parameters from sample statistics, hypothesis testing, other interesting articles, frequently asked questions about inferential statistics.
Descriptive statistics allow you to describe a data set, while inferential statistics allow you to make inferences based on a data set.
Using descriptive statistics, you can report characteristics of your data:
In descriptive statistics, there is no uncertainty – the statistics precisely describe the data that you collected. If you collect data from an entire population, you can directly compare these descriptive statistics to those from other populations.
Most of the time, you can only acquire data from samples, because it is too difficult or expensive to collect data from the whole population that you’re interested in.
While descriptive statistics can only summarize a sample’s characteristics, inferential statistics use your sample to make reasonable guesses about the larger population.
With inferential statistics, it’s important to use random and unbiased sampling methods . If your sample isn’t representative of your population, then you can’t make valid statistical inferences or generalize .
Since the size of a sample is always smaller than the size of the population, some of the population isn’t captured by sample data. This creates sampling error , which is the difference between the true population values (called parameters) and the measured sample values (called statistics).
Sampling error arises any time you use a sample, even if your sample is random and unbiased. For this reason, there is always some uncertainty in inferential statistics. However, using probability sampling methods reduces this uncertainty.
The characteristics of samples and populations are described by numbers called statistics and parameters :
Sampling error is the difference between a parameter and a corresponding statistic. Since in most cases you don’t know the real population parameter, you can use inferential statistics to estimate these parameters in a way that takes sampling error into account.
There are two important types of estimates you can make about the population: point estimates and interval estimates .
Both types of estimates are important for gathering a clear idea of where a parameter is likely to lie.
A confidence interval uses the variability around a statistic to come up with an interval estimate for a parameter. Confidence intervals are useful for estimating parameters because they take sampling error into account.
While a point estimate gives you a precise value for the parameter you are interested in, a confidence interval tells you the uncertainty of the point estimate. They are best used in combination with each other.
Each confidence interval is associated with a confidence level. A confidence level tells you the probability (in percentage) of the interval containing the parameter estimate if you repeat the study again.
A 95% confidence interval means that if you repeat your study with a new sample in exactly the same way 100 times, you can expect your estimate to lie within the specified range of values 95 times.
Although you can say that your estimate will lie within the interval a certain percentage of the time, you cannot say for sure that the actual population parameter will. That’s because you can’t know the true value of the population parameter without collecting data from the full population.
However, with random sampling and a suitable sample size, you can reasonably expect your confidence interval to contain the parameter a certain percentage of the time.
Your point estimate of the population mean paid vacation days is the sample mean of 19 paid vacation days.
Hypothesis testing is a formal process of statistical analysis using inferential statistics. The goal of hypothesis testing is to compare populations or assess relationships between variables using samples.
Hypotheses , or predictions, are tested using statistical tests . Statistical tests also estimate sampling errors so that valid inferences can be made.
Statistical tests can be parametric or non-parametric. Parametric tests are considered more statistically powerful because they are more likely to detect an effect if one exists.
Parametric tests make assumptions that include the following:
When your data violates any of these assumptions, non-parametric tests are more suitable. Non-parametric tests are called “distribution-free tests” because they don’t assume anything about the distribution of the population data.
Statistical tests come in three forms: tests of comparison, correlation or regression.
Comparison tests assess whether there are differences in means, medians or rankings of scores of two or more groups.
To decide which test suits your aim, consider whether your data meets the conditions necessary for parametric tests, the number of samples, and the levels of measurement of your variables.
Means can only be found for interval or ratio data , while medians and rankings are more appropriate measures for ordinal data .
test | Yes | Means | 2 samples |
---|---|---|---|
Yes | Means | 3+ samples | |
Mood’s median | No | Medians | 2+ samples |
Wilcoxon signed-rank | No | Distributions | 2 samples |
Wilcoxon rank-sum (Mann-Whitney ) | No | Sums of rankings | 2 samples |
Kruskal-Wallis | No | Mean rankings | 3+ samples |
Correlation tests determine the extent to which two variables are associated.
Although Pearson’s r is the most statistically powerful test, Spearman’s r is appropriate for interval and ratio variables when the data doesn’t follow a normal distribution.
The chi square test of independence is the only test that can be used with nominal variables.
Pearson’s | Yes | Interval/ratio variables |
---|---|---|
Spearman’s | No | Ordinal/interval/ratio variables |
Chi square test of independence | No | Nominal/ordinal variables |
Regression tests demonstrate whether changes in predictor variables cause changes in an outcome variable. You can decide which regression test to use based on the number and types of variables you have as predictors and outcomes.
Most of the commonly used regression tests are parametric. If your data is not normally distributed, you can perform data transformations.
Data transformations help you make your data normally distributed using mathematical operations, like taking the square root of each value.
1 interval/ratio variable | 1 interval/ratio variable | |
2+ interval/ratio variable(s) | 1 interval/ratio variable | |
Logistic regression | 1+ any variable(s) | 1 binary variable |
Nominal regression | 1+ any variable(s) | 1 nominal variable |
Ordinal regression | 1+ any variable(s) | 1 ordinal variable |
If you want to know more about statistics , methodology , or research bias , make sure to check out some of our other articles with explanations and examples.
Methodology
Research bias
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Descriptive statistics summarize the characteristics of a data set. Inferential statistics allow you to test a hypothesis or assess whether your data is generalizable to the broader population.
A statistic refers to measures about the sample , while a parameter refers to measures about the population .
A sampling error is the difference between a population parameter and a sample statistic .
Hypothesis testing is a formal procedure for investigating our ideas about the world using statistics. It is used by scientists to test specific predictions, called hypotheses , by calculating how likely it is that a pattern or relationship between variables could have arisen by chance.
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Bhandari, P. (2023, June 22). Inferential Statistics | An Easy Introduction & Examples. Scribbr. Retrieved August 21, 2024, from https://www.scribbr.com/statistics/inferential-statistics/
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Probability And Statistics are the two important concepts in Maths. Probability is all about chance. Whereas statistics is more about how we handle various data using different techniques. It helps to represent complicated data in a very easy and understandable way. Statistics and probability are usually introduced in Class 10, Class 11 and Class 12 students are preparing for school exams and competitive examinations. The introduction of these fundamentals is briefly given in your academic books and notes. The statistic has a huge application nowadays in data science professions. The professionals use the stats and do the predictions of the business. It helps them to predict the future profit or loss attained by the company.
Table of contents:
What is probability.
Probability denotes the possibility of the outcome of any random event. The meaning of this term is to check the extent to which any event is likely to happen. For example, when we flip a coin in the air, what is the possibility of getting a head ? The answer to this question is based on the number of possible outcomes. Here the possibility is either head or tail will be the outcome. So, the probability of a head to come as a result is 1/2.
The probability is the measure of the likelihood of an event to happen. It measures the certainty of the event. The formula for probability is given by;
P(E) = Number of Favourable Outcomes/Number of total outcomes
P(E) = n(E)/n(S)
n(E) = Number of event favourable to event E
n(S) = Total number of outcomes
Statistics is the study of the collection, analysis, interpretation, presentation, and organization of data. It is a method of collecting and summarising the data. This has many applications from a small scale to large scale. Whether it is the study of the population of the country or its economy, stats are used for all such data analysis.
Statistics has a huge scope in many fields such as sociology, psychology, geology, weather forecasting, etc. The data collected here for analysis could be quantitative or qualitative. Quantitative data are also of two types such as: discrete and continuous. Discrete data has a fixed value whereas continuous data is not a fixed data but has a range. There are many terms and formulas used in this concept. See the below table to understand them .
There are various terms utilised in the probability and statistics concepts, Such as:
Let us discuss these terms one by one.
An experiment whose result cannot be predicted, until it is noticed is called a random experiment. For example, when we throw a dice randomly, the result is uncertain to us. We can get any output between 1 to 6. Hence, this experiment is random.
A sample space is the set of all possible results or outcomes of a random experiment. Suppose, if we have thrown a dice, randomly, then the sample space for this experiment will be all possible outcomes of throwing a dice, such as;
Sample Space = { 1,2,3,4,5,6}
The variables which denote the possible outcomes of a random experiment are called random variables. They are of two types:
Discrete random variables take only those distinct values which are countable. Whereas continuous random variables could take an infinite number of possible values.
When the probability of occurrence of one event has no impact on the probability of another event, then both the events are termed as independent of each other. For example, if you flip a coin and at the same time you throw a dice, the probability of getting a ‘head’ is independent of the probability of getting a 6 in dice.
Mean of a random variable is the average of the random values of the possible outcomes of a random experiment. In simple terms, it is the expectation of the possible outcomes of the random experiment, repeated again and again or n number of times. It is also called the expectation of a random variable.
Expected value is the mean of a random variable. It is the assumed value which is considered for a random experiment. It is also called expectation, mathematical expectation or first moment. For example, if we roll a dice having six faces, then the expected value will be the average value of all the possible outcomes, i.e. 3.5.
Basically, the variance tells us how the values of the random variable are spread around the mean value. It specifies the distribution of the sample space across the mean.
Basic probability topics are :
Addition Rule of Probability | Binomial Probability | |
Compound Events | Compound Probability | Complementary Events |
Complementary Events | Coin Toss Probability | |
Geometric Probability | ||
Properties of Probability | Probability Line | Probability without Replacement |
Simple Event | ||
Basic Statistics topics are:
Box and Whisker Plots | Comparing Two Means | Comparing Two Proportions |
Degree of freedom | Empirical Rule | |
Five Number Summary | ||
Data Range | ||
Scatter Plots | ||
Ungrouped Data |
Probability Formulas : For two events A and B:
Probability Range | Probability of an event ranges from 0 to 1 i.e. 0 ≤ P(A) ≤ 1 |
Rule of Complementary Events | P(A’) + P(A) = 1 |
Rule of Addition | P(A∪B) = P(A) + P(B) – P(A∩B) |
Mutually Exclusive Events | P(A∪B) = P(A) + P(B) |
Independent Events | P(A∩B) = P(A)P(B) |
Disjoint Events | P(A∩B) = 0 |
Conditional Probability | P(A|B) = P(A∩B)/P(B) |
Bayes Formula | P(A|B) = P(B|A) P(A)/P(B) |
Statistics Formulas : Some important formulas are listed below:
Let x be an item given and n is the total number of items.
Mean | Mean = (Sum of all the terms)/(Total number of terms)
|
Median |
|
Mode | The most frequently occurring value |
Standard Deviation | |
Variance |
Here are some examples based on the concepts of statistics and probability to understand better. Students can practice more questions based on these solved examples to excel in the topic. Also, make use of the formulas given in this article in the above section to solve problems based on them.
Example 1 : Find the mean and mode of the following data: 2, 3, 5, 6, 10, 6, 12, 6, 3, 4.
Total Count: 10
Sum of all the numbers: 2+3+5+6+10+6+12+6+3+7=60
Mean = (sum of all the numbers)/(Total number of items)
Mean = 60/10 = 6
Again, Number 6 is occurring for 3 times, therefore Mode = 6. Answer
Example 2: A bucket contains 5 blue, 4 green and 5 red balls. Sudheer is asked to pick 2 balls randomly from the bucket without replacement and then one more ball is to be picked. What is the probability he picked 2 green balls and 1 blue ball?
Solution : Total number of balls = 14
Probability of drawing
1 green ball = 4/14
another green ball = 3/13
1 blue ball = 5/12
Probability of picking 2 green balls and 1 blue ball = 4/14 * 3/13 * 5/12 = 5/182.
Example 3 : What is the probability that Ram will choose a marble at random and that it is not black if the bowl contains 3 red, 2 black and 5 green marbles.
Solution : Total number of marble = 10
Red and Green marbles = 8
Find the number of marbles that are not black and divide by the total number of marbles.
So P(not black) = (number of red or green marbles)/(total number of marbles)
Example 4: Find the mean of the following data:
55, 36, 95, 73, 60, 42, 25, 78, 75, 62
Solution: Given,
55 36 95 73 60 42 25 78 75 62
Sum of observations = 55 + 36 + 95 + 73 + 60 + 42 + 25 + 78 + 75 + 62 = 601
Number of observations = 10
Mean = 601/10 = 60.1
Example 5: Find the median and mode of the following marks (out of 10) obtained by 20 students:
4, 6, 5, 9, 3, 2, 7, 7, 6, 5, 4, 9, 10, 10, 3, 4, 7, 6, 9, 9
Ascending order: 2, 3, 3, 4, 4, 4, 5, 5, 6, 6, 6, 7, 7, 7, 9, 9, 9, 9, 10, 10
Number of observations = n = 20
Median = (10th + 11th observation)/2
= (6 + 6)/2
Most frequent observations = 9
Hence, the mode is 9.
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Assignments.
The assignments for Concepts in Statistics are typically centered around a dataset that the student uses in conjunction with a statistics package. The activity has the student explore the dataset, generate descriptive statistics and appropriate graphs from the data, and interpret the output. Instructions are provided for five different statistics packages:
If you import this course into your learning management system (Blackboard, Canvas, etc.), the assignments will automatically be loaded into the assignment tool. They can be used as is, modified, or removed. You can preview them below:
Assignments and Alignment | |
---|---|
Assignment | Module |
Module 2: Summarizing Data Graphically and Numerically | |
Module 2: Summarizing Data Graphically and Numerically | |
Module 2: Summarizing Data Graphically and Numerically | |
Module 2: Summarizing Data Graphically and Numerically | |
Module 2: Summarizing Data Graphically and Numerically | |
Module 3: Examining Relationships: Quantitative Data | |
Module 3: Examining Relationships: Quantitative Data | |
Module 3: Examining Relationships: Quantitative Data | |
Module 3: Examining Relationships: Quantitative Data | |
Module 8: Inference for One Proportion | |
Module 9: Inference for Two Proportions | |
Module 10: Inference for Means | |
Module 10: Inference for Means | |
Module 10: Inference for Means | |
Module 10: Inference for Means | |
Module 10: Inference for Means | |
Module 10: Inference for Means | |
Module 10: Inference for Means | |
Module 11: Chi-Square Tests |
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NCHS Data Brief No. 507, August 2024
PDF Version (454 KB)
Joyce A. Martin, M.P.H., Brady E. Hamilton Ph.D., and Michelle J.K. Osterman, M.H.S.
Birth rates declined for females ages 15–19 from 2022 to 2023., prenatal care beginning in the first trimester declined for the second year in a row in 2023., the preterm birth rate was unchanged from 2022 to 2023, but early-term births increased., data source and methods, about the authors, suggested citation.
Data from the National Vital Statistics System
This report presents highlights from 2023 final birth data on key demographic and maternal and infant health indicators. The number of births, the general fertility rate (births per 1,000 females ages 15–44), teen birth rates, the distribution of births by trimester prenatal care began, and the distribution of births by gestational age (less than 37 weeks, 37–38 weeks, 39–40 weeks, and 41 or later weeks of gestation) are presented. For all indicators, results for 2023 are compared with those for 2022 and 2021.
Keywords : general fertility rate, prenatal care, gestational age, National Vital Statistics System.
Figure 1. Number of live births and general fertility rates: United States, 2021–2023
Year | Births | Fertility rate |
---|---|---|
2021 | 3,664,292 | 56.3 |
2022 | 3,667,758 | 56.0 |
2023 | 3,596,017 | 54.5 |
NOTES: General fertility rates are births per 1,000 women ages 15–44. Rates are based on population estimates as of July 1 for 2021, 2022, and 2023. SOURCE: National Center for Health Statistics, National Vital Statistics System, natality data file.
Figure 2. Birth rate for teenagers, by maternal age: United States, 2021–2023
Maternal age | ||||
---|---|---|---|---|
Year | 15–19 | 15–17 | 18–19 | |
Percentage | ||||
2002 | 13.9 | 5.6 | 26.6 | |
2003 | 13.6 | 5.6 | 25.8 | |
2004 | 13.1 | 5.5 | 24.6 |
NOTES: Age-specific birth rates are births per 1,000 females in specified age group. Rates are based on population estimates as of July 1 for each year 2021–2023. SOURCE: National Center for Health Statistics, National Vital Statistics System, natality data file.
Figure 3. Distribution of trimester prenatal care began: United States, 2021–2023
Trimester | ||||
---|---|---|---|---|
2021 | 2022 | 2023 | ||
Percentage | ||||
First trimester | 78.3 | 77.0 | 76.1 | |
Second trimester | 15.4 | 16.3 | 16.9 | |
Third trimester | 4.2 | 4.6 | 4.7 | |
No care | 2.1 | 2.2 | 2.3 |
SOURCE: National Center for Health Statistics, National Vital Statistics System, natality data file.
Figure 4. Distribution of births by gestational age: United States, 2021–2023
Gestational age | ||||
---|---|---|---|---|
Year | Preterm | Early term | Full term | Late and post term |
Percentage | ||||
2021 | 10.49 | 28.76 | 55.9 | 4.85 |
2022 | 10.38 | 29.31 | 55.32 | 4.99 |
2023 | 10.41 | 29.84 | 54.94 | 4.82 |
NOTES: Preterm is less than 37 weeks, early term is 37 to 38 weeks, full term is 39 to 40 weeks, and late and post-term is 41 weeks or more. Source: National Center for Health Statistics, National Vital Statistics System, natality data file. SOURCE: National Center for Health Statistics, National Vital Statistics System, natality data file.
U.S. birth certificate data for 2023 show continued declines in the number (2%) and rate (3%) of births from 2022 to 2023. Since the most recent high in 2007, the number of births has declined 17%, and the general fertility rate has declined 21% ( 1 ). The teen birth rate also continued to decline in 2023 and has declined two-thirds since 2007 ( 1 ). The percentage of women beginning care in the first trimester of pregnancy declined in 2023 and was down 3% from the most recent high in 2021; first trimester care had been on the rise from 2016 to 2021. At the same time, the percentage of women with late care or with no care rose from 2021 to 2023; late and no-care levels have risen steadily since 2016 ( 1 ). The preterm birth rate was essentially unchanged from 2022 to 2023, but early-term births rose 2%, and full-term and late- and post-term births declined 1% and 3%, respectively. Since the most recent low in 2014, preterm birth rates have risen 9% and early-term births by 21%, while full-term and late- and post-term births have declined ( 1 ).
General fertility rate : Number of births per 1,000 females ages 15–44.
Gestational age : Preterm is births delivered before 37 completed weeks of gestation, early term is 37–38 weeks, full term is 39–40 weeks, and late and post term is 41 or later weeks. Gestational age is based on the obstetric estimate of gestation in completed weeks.
Teenage birth rates : Births per 1,000 females in the specified age groups 15–19, 15–17, and 18–19.
Trimester prenatal care began : The timing of care based on the date a physician or other health care provider examined or counseled the pregnant woman for the pregnancy and the obstetric estimate of gestational age.
This report uses data from the natality data file from the National Vital Statistics System. The vital statistics natality file is based on information from birth certificates and includes information for all births occurring in the United States. This Data Brief accompanies the release of the 2023 natality public-use file ( 2 ). More detailed analyses of the topics presented in this report and other topics such as births by age of mother, tobacco use during pregnancy, pregnancy risk factors, prenatal care timing and utilization, receipt of WIC food, maternal body mass index, and breastfeeding are possible by using the annual natality files ( 2 ). Additional information from the 2023 final birth data file is available via the CDC WONDER platform and will be included in the final 2023 National Vital Statistics Births Report.
References to increases or decreases in rates or percentages indicate differences are statistically significant at the 0.05 level based on a two-tailed z test. References to decreases in the number of births indicate differences are statistically significant at the 0.05 level based on a two-tailed chi-squared test. Computations exclude records for which information is unknown.
Rates shown in this report are based on population estimates calculated from a base that incorporates the 2020 census, vintage 2020 estimates for April 1, 2020, and 2020 demographic analysis estimates. Rates are calculated based on population estimates as of July 1, 2022, (vintage 2022) and July 1, 2023 (vintage 2023) ( 1 , 3 ). The vintage 2023 population estimates include methodological changes made after the release of the vintage 2022 population estimates and projection ( 4 , 5 ). Changes in rates from 2022 to 2023 reflect changes in births and changes in population estimates.
Joyce A. Martin, Brady E. Hamilton, and Michelle J.K. Osterman are with the National Center for Health Statistics, Division of Vital Statistics.
Martin JA, Hamilton BE, Osterman MJK. Births in the United States, 2023. NCHS Data Brief, no 507. Hyattsville, MD: National Center for Health Statistics. 2024. DOI: https://dx.doi.org/10.15620/cdc/158789 .
All material appearing in this report is in the public domain and may be reproduced or copied without permission; citation as to source, however, is appreciated.
Brian C. Moyer, Ph.D., Acting Director Amy M. Branum, Ph.D., Associate Director for Science
Paul D. Sutton, Ph.D., Acting Director Andrés A. Berruti, Ph.D., M.A., Associate Director for Science
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This release of experimental statistics on Scottish VAT assignment will include the 2022 estimate and further historical estimates in the back series. The VAT assignment model calculates the Scottish share of UK VAT for the purposes of Scottish VAT assignment. This release will be published at 9:30am on 26 September 2024. If you have any further queries, please contact: [email protected]
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Fact-checking dnc night 2: what democratic speakers got right, wrong.
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Former President Barack Obama speaks Aug. 20, 2024, at the Democratic National Convention in Chicago. (AP)
CHICAGO — Two decades after exploding onto the political scene at a different Democratic convention, former President Barack Obama, along with former first lady Michelle Obama, energized convention attendees here. The Obamas bestowed their support on nominee Kamala Harris, who aims to follow Barack Obama as the nation’s second Black president.
Barack Obama began his address by praising outgoing President Joe Biden. "I am proud to call him my president, but I am even prouder to call him my friend," Obama said of Biden, his former vice president.
Obama attacked Harris’ opponent, former President Donald Trump with zingers, once needling Trump for a " weird obsession with crowd sizes " (which also involved a suggestive hand gesture).
Barack Obama offered a few notes that rhymed with his career-making 2004 keynote address at the Democratic convention in Boston, in which he argued against the idea that there is a blue America and a red America.
Michelle Obama’s speech also offered some optimistic notes, including the notion that "hope is making a comeback" with Harris’ late entry into the presidential race as Biden’s would-be successor. But the former first lady’s remarks were sometimes even more acerbic than her husband’s.
She said, for example, that Trump had benefited from the "affirmative action of generational wealth" yet still managed to get "a second, third or fourth chance" while regularly "whining" or "cheating." She also criticized Trump — an early spreader of the "birther" conspiracy theory that doubted that Obama was born in the U.S. — for having made Americans "fear us" as an educated, high-achieving couple who "happen to be Black."
PolitiFact fact-checks politicians across the political spectrum. We also fact-checked the Republican National Convention in July. Read more about our process.
Here are some fact-checks of claims made during the convention’s second night.
Barack Obama: Under Joe Biden, the U.S. produced "15 million jobs, higher wages, lower health care costs."
He’s right about jobs: The U.S. has added 15.8 million jobs since January 2021, when Biden was sworn in, though some of those represented the workforce return of workers the pandemic had sidelined.
Wages are up under Biden without factoring in inflation. But for his full tenure, wages have trailed inflation , which hit a four-decade high under Biden. Nevertheless, wages have outpaced inflation over the past two years, the past year and compared with before the pandemic.
Whether health care costs were lower overall is a trickier question, because there’s great variation from family to family and person to person. However, U.S. health care expenditures as a percentage of gross domestic product peaked during the pandemic in 2020 and have since fallen roughly to prepandemic levels. This represented the biggest sustained decline in decades.
LIVE BLOG: Explore PolitiFact’s live fact-checking feed from Night 2 of DNC 2024
Sen. Bernie Sanders, I-Vt.: "Unemployment was soaring" when Biden and Harris took office in January 2021.
Mostly False.
Sanders overstated the unemployment situation that existed when Biden and Harris were inaugurated.
In April 2020, at the start of the COVID-19 pandemic, the unemployment rate surged to 14.8% as millions of Americans lost their jobs.
But by the time Biden took office in January 2021, the rate had fallen to 6.4%, and it continued to fall that year. So it wasn’t "soaring" any longer, though the rate was still high by historical standards. It was lower than 6.4% for about six years prepandemic.
July’s unemployment rate is 4.3%.
Pennsylvania state Rep. Malcolm Kenyatta, D-Philadelphia: "And on Page 587, Project 2025 would cut overtime pay for hardworking Americans."
Labor law experts have told PolitiFact that the Project 2025 plan would not eliminate overtime pay, but some workers could lose overtime protections if the plan’s proposals are enacted. It’s hard to say how many; it would depend on what’s enacted.
The document proposes that the Labor Department maintain an overtime threshold "that does not punish businesses in lower-cost regions (e.g., the southeast United States)." This threshold is the amount of money executive, administrative or professional employees need to make for an employer to exempt them from overtime pay under the Fair Labor Standards Act.
In 2019, the Trump administration finalized a rule that expanded overtime pay eligibility to most salaried workers earning less than about $35,568. The Biden administration raised that threshold to $43,888 beginning July 1, and that will rise to $58,656 on Jan. 1, 2025. Project 2025’s proposal would return to the Trump-era threshold in some parts of the country. It’s unclear how many workers that would affect, but experts said some would presumably lose the right to overtime wages.
Other proposals in the plan include allowing some workers to choose to accumulate paid time off instead of overtime pay, to work more hours in one week and fewer in the next rather than receive overtime and requiring employers to pay overtime for working on the Sabbath.
Former first lady Michelle Obama: One of Trump’s proposals is "shutting down the Department of Education."
Trump has said he would abolish the Education Department , a proposal he shares with Project 2025 , an agenda independently produced by some Trump allies.
It’s also something conservative groups have pushed for decades. The idea is to save a few essential functions and hand them to other agencies.
Trump’s education agenda also includes universal school choice, not spending federal dollars on schools that have vaccine mandates, allowing prayer in school, making principals directly elected by voters, subsidizing homeschooling and abolishing tenure for K-12 teachers.
Sen. Chuck Schumer, D-N.Y.: "Democrats lowered prescription drug prices."
Mostly True.
The Democrats did take historic steps to lower prices for Medicare recipients, but that’s a limited group of people and for many drugs that will take time.
In August 2022, Biden signed the Inflation Reduction Act, which allows the federal government to negotiate prices with drugmakers for Medicare. It passed without Republican support. The same law capped the monthly price of insulin at $35 for Medicare enrollees starting in 2023.
The Biden-Harris administration announced Aug. 15 that the federal government had reached agreements with all participating manufacturers on new negotiated drug prices for the first 10 drugs selected under the new law.
That will define the prices to be paid for prescriptions starting in 2026. For 2027 and 2028, 15 more drugs per year will be chosen for price negotiations. Starting in 2029, 20 more will be chosen a year.
New Mexico Gov. Michelle Lujan Grisham: Donald Trump and J.D. Vance want to "repeal the Affordable Care Act."
Half True .
Trump’s new position doesn’t match his old one, but more details are needed.
In 2016, Trump campaigned on a promise to repeal and replace the Affordable Care Act. As president, Trump supported a failed effort to do just that. In the years since, he has repeatedly stated his intent to dismantle the health care law, including in campaign stops and social media posts throughout 2023.
In March, however, Trump walked back this stance. He wrote on Truth Social that he "isn’t running to terminate" the ACA but to make it "better" and "less expensive."
Trump hasn’t said how he would do this, and health care policy experts said it’s difficult to know where he stands absent a detailed plan. Experts identified an array of possible changes that another Trump administration could execute but said a sweeping repeal likely isn’t in the cards given a lack of political support.
Sanders: "We cut childhood poverty by over 40% through an expanded child tax credit."
Biden’s American Rescue Plan increased the child tax credit from $2,000 to $3,600 for children younger than 6 and to $3,000 for children 6 to 17.
We previously reported that supplemental poverty numbers showed poverty among all U.S. children dropped from 9.7% in 2020 to 5.2% in 2021, the Census Bureau said — a decline of 46%. About 5.3 million people were lifted out of poverty, including 2.9 million children.
The provision lapsed after December 2021, facing opposition from Republicans and Sen. Joe Manchin, now an independent, who argued that expanding the credit would worsen inflation.
When the expanded tax credit expired, supplemental child poverty spiked , rising from 12.1% in December 2021 to 17% in January 2022 — a 41% change.
Kamala Harris in a DNC video: Trump "wants to impose what is in effect a national sales tax on everyday products and basic necessities that we import from other countries. … (it) would cost a typical family $3,900 a year."
Trump has said that he would propose a 10% tariff on all nondomestic goods sold in the U.S. Although tariffs are levied separately from taxes, economists say that much of their impact would be passed along to consumers, making them analogous to a tax.
The video’s figure about how much it will cost families is higher than current estimates.
The American Action Forum, a center-right think tank, has projected additional costs per household of $1,700 to $2,350 annually.
The Peterson Institute of International Economics, another Washington, D.C.-based think tank, projected that such tariffs would cost a middle-income household about $1,700 extra each year.
PolitiFact Chief Correspondent Louis Jacobson, Senior Correspondent Amy Sherman, Staff Writers Jeff Cercone, Samantha Putterman, Sara Swann, Loreben Tuquero and Maria Ramirez Uribe contributed to this story.
Our convention fact-checks rely on both new and previously reported work. We link to past work whenever possible. In some cases, a fact-check rating may be different tonight than in past versions. In those cases, either details of what the candidate said, or how the candidate said it, differed enough that we evaluated it anew.
Please see sources linked in story.
More by politifact staff.
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Statistics Definition: Statistics is a branch that deals with every aspect of the data. Statistical knowledge helps to choose the proper method of collecting the data and employ those samples in the correct analysis process in order to effectively produce the results. In short, statistics is a crucial process which helps to make the decision ...
Statistics is the study of the collection, analysis, interpretation, presentation, and organization of data. In other words, it is a mathematical discipline to collect, summarize data. Also, we can say that statistics is a branch of applied mathematics. However, there are two important and basic ideas involved in statistics; they are ...
There are statistics about crime, sports, education, politics, and real estate. Typically, when you read a newspaper article or watch a television news program, you are given sample information. With this information, you may make a decision about the correctness of a statement, claim, or "fact." Statistical methods can help you make the "best ...
Statistics is a mathematical body of science that pertains to the collection, analysis, interpretation or explanation, and presentation of data, [8] or as a branch of mathematics. [9] Some consider statistics to be a distinct mathematical science rather than a branch of mathematics. While many scientific investigations make use of data, statistics is generally concerned with the use of data in ...
Table of contents. Step 1: Write your hypotheses and plan your research design. Step 2: Collect data from a sample. Step 3: Summarize your data with descriptive statistics. Step 4: Test hypotheses or make estimates with inferential statistics.
Key Terms. In statistics, we generally want to study a population.You can think of a population as a collection of persons, things, or objects under study. To study the population, we select a sample.The idea of sampling is to select a portion (or subset) of the larger population and study that portion (the sample) to gain information about the population.
Learn for free about math, art, computer programming, economics, physics, chemistry, biology, medicine, finance, history, and more. Khan Academy is a nonprofit with the mission of providing a free, world-class education for anyone, anywhere.
Introduction to Statistics is a resource for learning and teaching introductory statistics. This work is in the public domain. Therefore, it can be copied and reproduced without limitation. However, we would appreciate a citation where possible. ... The text dose lend itself to reasonable reading assignments. For example the chapter (Chapter 3 ...
Khanmigo is now free for all US educators! Plan lessons, develop exit tickets, and so much more with our AI teaching assistant.
Statistics is a study of data: describing properties of data (descriptive statistics) and drawing conclusions about a population based on information in a sample (inferential statistics). The distinction between a population together with its parameters and a sample together with its statistics is a fundamental concept in inferential statistics ...
Statistics is a branch of mathematics used to summarize, analyze, and interpret a group of numbers or observations. We begin by introducing two general types of statistics: •• Descriptive statistics: statistics that summarize observations. •• Inferential statistics: statistics used to interpret the meaning of descriptive statistics.
The Role of Statistics ! Despite the anxiety usually associated with statistics, data analysis is a relatively small piece of the larger research process. ! There is a misconception that the trustworthiness of statistics is independent of the research process itself. ! This is absolutely incorrect! !
Statistics may be defined as the collection, presentation, analysis and interpretation of numerical data. Statistics is a set of decision-making techniques which helps businessmen in making suitable policies from the available data. In fact, every businessman needs a sound background of statistics as well as of mathematics.
Statistics is a form of mathematical analysis that uses quantified models, representations and synopses for a given set of experimental data or real-life studies. Statistics studies methodologies ...
Types of descriptive statistics. There are 3 main types of descriptive statistics: The distribution concerns the frequency of each value. The central tendency concerns the averages of the values. The variability or dispersion concerns how spread out the values are. You can apply these to assess only one variable at a time, in univariate ...
Types of descriptive statistics. There are 3 main types of descriptive statistics: The distribution concerns the frequency of each value. The central tendency concerns the averages of the values. The variability or dispersion concerns how spread out the values are. You can apply these to assess only one variable at a time, in univariate ...
Random assignment is a fundamental part of a "true" experiment because it helps ensure that any differences found between the groups are attributable to the treatment, rather than a confounding variable. So, to summarize, random sampling refers to how you select individuals from the population to participate in your study.
Random selection and random assignment are two techniques in statistics that are commonly used, but are commonly confused.. Random selection refers to the process of randomly selecting individuals from a population to be involved in a study.. Random assignment refers to the process of randomly assigning the individuals in a study to either a treatment group or a control group.
Example: Inferential statistics. You randomly select a sample of 11th graders in your state and collect data on their SAT scores and other characteristics. You can use inferential statistics to make estimates and test hypotheses about the whole population of 11th graders in the state based on your sample data.
Whereas statistics is more about how we handle various data using different techniques. It helps to represent complicated data in a very easy and understandable way. Statistics and probability are usually introduced in Class 10, Class 11 and Class 12 students are preparing for school exams and competitive examinations.
Introduction; 9.1 Null and Alternative Hypotheses; 9.2 Outcomes and the Type I and Type II Errors; 9.3 Distribution Needed for Hypothesis Testing; 9.4 Rare Events, the Sample, and the Decision and Conclusion; 9.5 Additional Information and Full Hypothesis Test Examples; 9.6 Hypothesis Testing of a Single Mean and Single Proportion; Key Terms; Chapter Review; Formula Review
Assignments. The assignments for Concepts in Statistics are typically centered around a dataset that the student uses in conjunction with a statistics package. The activity has the student explore the dataset, generate descriptive statistics and appropriate graphs from the data, and interpret the output. Instructions are provided for five ...
Khan Academy
This report presents highlights from 2023 final birth data on key demographic and maternal and infant health indicators. The number of births, the general fertility rate (births per 1,000 females ages 15-44), teen birth rates, the distribution of births by trimester prenatal care began, and the distribution of births by gestational age (less than 37 weeks, 37-38 weeks, 39-40 weeks, and ...
This release of experimental statistics on Scottish VAT assignment will include the 2022 estimate and further historical estimates in the back series. The VAT assignment model calculates the ...
That will define the prices to be paid for prescriptions starting in 2026. For 2027 and 2028, 15 more drugs per year will be chosen for price negotiations. Starting in 2029, 20 more will be chosen ...