Probability Distributions > The arcsine distribution and the generalized arcsine distribution are found in the study of random walk fluctuation, renewal theory, and as the Jeffrey’s prior for successes in a Bernoulli trial. The generalized arcsine distribution, used in mathematical…

## Von Mises Fisher Distribution

Probability Distributions > The Von Mises Fisher Distribution (vMF) is an important isotropic distribution for directional data and statistics. “Directional” statistics are simply statistics that have direction as well as magnitude, like gene expression data, wind current directions or measurements…

## Reservoir Sampling

Sampling > Reservoir sampling is a quota-based random sampling method, used to get a sample of a particular size when you don’t know the population size (i.e. when you’re dealing with a data stream of unknown length). The reservoir can…

## Oversampling in Statistics

Sampling > Oversampling in Statistics In statistics, oversampling involves taking higher, disproportionate samples than would otherwise be collected with random sampling. Depending on the structure of the survey or poll, oversampling might result in bringing low numbers of an underrepresented…

## Collider Variable: Definition

Descriptive Statistics > What is a Collider Variable? Graphically, a node on a causal graph (a type of directed acyclic graph) is a collider variable if the path entering and exiting the node both have arrows pointing into it. Essentially,…

## Undersampling and Oversampling in Data Analysis

Sampling > Undersampling in data analysis is a technique that attempts to reduce the bias associated with imbalanced classes of data. Undersampling combined with oversampling, are two techniques that deal with imbalances in a training set. You can undersample the…

## Absolute Frequency: Definition, Examples

Descriptive Statistics > Absolute frequency is a simple count of the number of cases, items, or things. An absolute frequency distribution displays those counts, usually in a table. Creating an Absolute Frequency Distribution The set up for an absolute frequency…

## Communality

Principal Component Analysis > In PCA and Factor Analysis, a variable’s communality is a useful measure for predicting the variable’s value. More specifically, it tells you what proportion of the variable’s variance is a result of either: The principal components…

## Adjusted Odds Ratio

Statistics Definitions > You may want to read this article first: What is an Odds Ratio? What is an Adjusted Odds Ratio? An adjusted odds ratio (AOR) is an odds ratio that controls for other predictor variables in a model.…

## Beta Geometric Distribution (Type I Geometric)

Probability Distributions > What is the Beta Geometric Distribution? The beta geometric distribution (also called the Type I Geometric) is a type of geometric distribution, where the probability of success parameter, p, has a Beta distribution with shape parameters alpha(α)…