# Statistics How To

## Irwin–Hall Distribution

Probability Distributions > The Irwin-Hall distribution (Uniform Sum Distribution) is the distribution of the sum of n values taken from the uniform distribution U(0, 1). It is similar to the Bates distribution, which is the distribution of the mean of…

## Johansen’s Test: Simple Definition

Cointegration > Johansen’s test is a way to determine if three or more time series are cointegrated. More specifically, it assesses the validity of a cointegrating relationship, using a maximum likelihood estimates (MLE) approach. It is also used to find…

## Wording Bias

Bias > Wording bias, also called question-wording bias or “leading on the reader” (Gerver & Sgroi, 2017) happens in a survey when the wording of a question systematically influences the responses (Hinders, 2019). Examples of Wording Bias If a survey…

## Mallows’ Cp

Regression Analysis > Mallows’ Cp Criterionis a way to assess the fit of a multiple regression model. The technique then compares the full model with a smaller model with “p” parameters and determines how much error is left unexplained by…

## Pooled Variance

Statistics Definitions > Pooled variance (also called combined, composite, or overall variance) is a way to estimate common variance when you believe that different populations have the same variances. The pooled sample variance formula is: Where: n = the sample…

## Pruning

Statistics Definitions > Pruning removes parts of a model that are non-predictive. The process discards statistical noise, reducing the model’s size and usually improving its accuracy. Pruning is often necessary because the number of potential subtrees grows as a function…

## Hypergeometric Distribution: Examples and Formula

Statistics Definitions > Hypergeometric Distribution The hypergeometric distribution is a probability distribution that’s very similar to the binomial distribution. In fact, the binomial distribution is a very good approximation of the hypergeometric distribution as long as you are sampling 5%…

## Fuzzy Statistics

Statistics Definitions > Fuzzy statistics usually refers to a combination of fuzzy set theory—the treatment of ambiguous, imprecise, or subjective data—and traditional statistical methods. It’s a very loose term that isn’t very well defined; It could apply to anything to…

## Plausibility, Plausible Values and Measures

Statistics Definitions > In a broad sense, plausibility is usually used as another name for “reasonable.” Let’s say you wanted to check a normal model, obtained from a sample, to see if it is a reasonable model for the population.…

## Prediction Function: Simple Definition, Examples

Statistics definitions > In general terms, a prediction function is a mathematical function that tells you something about a future event, based on past events. There are many different kinds of functions that might be classified as prediction functions, including…