Statistics How To

Statistics Definitions > Summary Statistics Summary statistics summarize and provide information about your sample data. It tells you something about the values in your data set. This includes where the mean lies and whether your data is skewed. Summary statistics fall into three main categories: Measures of location (also called central tendency). Measures of spread. … Read more

Statistics Definitions > Relative Standard Deviation What is a Relative Standard Deviation? The relative standard deviation (RSD) is a special form of the standard deviation (std dev). You may want to read this previous article first: How to find Standard Deviation The relative standard deviation formula is: 100 * s / |x̄| Where: s = … Read more

Statistics Definitions > Trimmed Mean A trimmed mean (sometimes called a truncated mean) is similar to a “regular” mean (average), but it trims any outliers. Outliers can affect the mean (especially if there are just one or two very large values), so a trimmed mean can often be a better fit for data sets with … Read more

Statistics Definitions > Univariate Analysis What is Univariate Analysis? Univariate analysis is the simplest form of analyzing data. “Uni” means “one”, so in other words your data has only one variable. It doesn’t deal with causes or relationships (unlike regression ) and it’s major purpose is to describe; It takes data, summarizes that data and … Read more

Types of Variable > Endogenous Variable and Exogenous Variable What are Endogenous Variables? Endogenous variables are used in econometrics and sometimes in linear regression. They are similar to (but not exactly the same as) dependent variables. Endogenous variables have values that are determined by other variables in the system (these “other” variables are called exogenous … Read more

Types of Variable > Dummy Variables What are Dummy Variables? Dummy variables (sometimes called indicator variables) are used in regression analysis and Latent Class Analysis. As implied by the name, these variables are artificial attributes, and they are used with two or more categories or levels. It’s used when you want to work with categorical … Read more

Binomial Theorem > Binomial test What is a binomial test? The binomial test is used when an experiment has two possible outcomes (i.e. success/failure) and you have an idea about what the probability of success is. A binomial test is run to see if observed test results differ from what was expected. Example: you theorize … Read more

Regression Analysis > You may want to read this article first: What is the Logit Model? What is Ordered Logistic Regression? Ordered Logistic Regression (also called the logit model or cumulative link model) is a sub-type of logistic regression where the Y-category is ordered. It is used when your dependent variable has: A meaningful order, … Read more

Statistics Definitions > Cohen’s Kappa Statistic What is Cohen’s Kappa Statistic? Cohen’s kappa statistic measures interrater reliability (sometimes called interobserver agreement). Interrater reliability, or precision, happens when your data raters (or collectors) give the same score to the same data item. This statistic should only be calculated when: Two raters each rate one trial on … Read more

Hypothesis Testing > MANCOVA < < Previous article: What is ANCOVA? What is MANCOVA? MANCOVA (Multivariate Analysis of Covariance) is the multivariate counterpart of ANCOVA. MANCOVA tells you if there are statistically significant mean differences among groups. In other words, it tells you if group differences probably happened by random chance, or if there is … Read more