Statistics How To

Statistics Definitions > What is Central Tendency? Central tendency (sometimes called measure of location, central location, or just center), attempts to describe an entire set of data with one figure — a statistic such as an average amount or a median price. Central tendency doesn’t tell you specifics about the individual pieces of data, but … Read more

Statistics Definitions > When you estimate a percentage from a fraction of a population, that’s called a sample percentage. Let’s say you wanted to find out how many people in the United States are women. According to the Census bureau, that figure — the population percentage — is 50.5%. But it’s not often that kind … Read more

Statistics Definitions > The idea of a population percentage often shows up when calculating confidence intervals. It is a type of population parameter [1], which means that it concerns everyone in the population — not just a sample. Population Percentage Example For example, the population of the United States in 2021 was 331.9 million. Of … Read more

Probability and Statistics > Sampling > What is a Sample? In statistics, you’ll be working with samples — a part of a population. For example, if you want to find out how much the average American earns, you aren’t going to want to survey everyone in the population (over 300 million people), so you would … Read more

Types of Variables > A criterion variable is another name for a dependent variable. However, the terms aren’t exactly interchangeable: a criterion variable is usually only used in non-experimental situations. For example, in statistical modeling applications like multiple regression and canonical correlation which use existing experimental data to make predictions. Use in Modeling In statistical … Read more

Hypothesis Testing > An omnibus test (also called a combined test) is an overall test for a whole group of results. For example, an ANOVA is an omnibus test — if you reject the null hypothesis, then one pair may have significant differences or all pairs may be significantly different. You may want to run … Read more

Hypothesis Testing > Contrast analysis is a way to provide more precise conclusions than a traditional analysis of variance for tests with factorial designs. While an F-Test will give you an idea of whether your independent variables have an effect on the study, a contrast test will tell you exactly where these differences appear. The … Read more

Probability and Statistics > Probability > Sample Space Examples Contents: What is a Sample Space? Large Sample Spaces The Counting Principle Continuous Sample Spaces What is a Sample Space? The sample space of an experiment is all possible outcomes for that experiment. For example: The space for the toss of one coin: {Heads, tails.} The … Read more

Statistics Definitions > The normalized root mean squared error (NRMSE), also called a scatter index, is a statistical error indicator defined as [1]. Where Oi are observed values and Si are simulated values. It can also be calculated as RMSE/range or RMSE/mean. Which formula you use depends on your data and the purpose for calculating … Read more

Statistics Definitions > Test Statistic A test statistic is used in a hypothesis test when you are deciding to support or reject the null hypothesis. The test statistic takes your data from an experiment or survey and compares your results to the results you would expect from the null hypothesis. The test statistic is a … Read more