Statistics How To

Types of Variables > A moderating variable, also called a moderator variable or simply M, changes the strength or direction of an effect between two variables x and y. In other words, it affects the relationship between the independent variable or predictor variable and a dependent variable or criterion variable. Types of Moderating Variable A … Read more

Probability Distribution > What is the Robust Soliton Distribution? Analysis of LT (Luby transform) codes is based on the analysis of the decoding algorithm, the LT processes. Each LT code symbol is generated by randomly selecting the degree of the code symbol, d, between 1 and k. The Robust Soliton distribution is a degree distribution, … Read more

Probability > What is the Probability of an Impossible Event? The probability of an impossible event is 0. Impossible events can’t occur. For example: What is the probability of rolling a 7 on a six-sided die? As the number 7 never appears on a face of a six-sided die, the event is impossible. Therefore, the … Read more

Excel for Statistics > Two Way ANOVA in Excel Contents: Two way ANOVA in Excel with Replication. Two way ANOVA in Excel without Replication. Two Way ANOVA in Excel with Replication ANOVA tests are used to determine whether you have significant results from tests (or surveys). A two way ANOVA with replication is performed when … Read more

Probability Distributions > In general, a non-central distribution is a transformation of a normal distribution. These transformation are defined by non-centrality parameters; If a non-centrality parameter (σ) is zero they are called central distributions. If σ is anything but zero, then they are non-central distributions. The term “non-central distribution” may refer to one of several … Read more

Statistics Definitions > What is Simpson’s Diversity Index? Simpson’s diversity index (SDI) measures community diversity. Although it’s commonly used to measure biodiversity, it can also be used to gauge diversity differences of populations in schools, communities and other locations. The range is from 0 to 1, where: High scores (close to 1) indicate high diversity. … Read more

Types of Variables > A mediator variable explains the how or why of an (observed) relationship between an independent variable and its dependent variable. In a mediation model, the independent variable cannot influence the dependent variable directly, and instead does so by means of a third variable, a ‘middle-man’. In psychology, the mediator variable is … Read more

Types of Variable > What is a Scale Variable? Scale variable doesn’t have an “official” definition; it’s one of those terms that has a slightly different meaning depending on where you’re using it. In a very general sense, the term is synonymous with measurement variable, although care should be taken to make sure this use … Read more

Statistics Definitions > What is Kernel Density Estimation? Kernel density estimation extrapolates data to an estimated population probability density function. It’s called kernel density estimation because each data point is replaced with a kernel—a weighting function to estimate the pdf. The function spreads the influence of any point around a narrow region surrounding the point. … Read more

Probability > Addition Rule Contents: Addition Rule Inclusion-Exclusion Probability The Addition Rule The addition rule is used to find the probability that an event “A” or “B” happens. This could be individually or both at the same time. Examples of events that might happen at the same time: Getting a parking ticket if you’re unable … Read more