We very often set the cutoff for a significant p value at 0.05, and minimal acceptable power at 0.8. Sometimes p of 0.01 is demanded. Sometimes power of 0.90 is demanded. But what are these values and how are they chosen? Read more!

Two terms that are frequently confused are *moderation* and *mediation*:

**Definitions of moderating and mediating:**

A mediating variable is one that accounts for or alters another relationship. A strict definition is that the mediating variable has to greatly reduce or even eliminate the relationship. A more lenient definition is that it affects the relationship. I favor that more lenient definition. A *moderating* variable is one that *interacts* with a variable. An *interaction *means that the relationship between one independent variable (IV) and the dependent variable (DV) is different at different levels of the *other *IV. Read more!

In regression models of various kinds (e.g. multiple linear regression, or various others) the result includes (by default) an intercept term.

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**Regression** is a set of statistical techniques for relating a **dependent variable** to one or more **independent variables.** Briefly, a dependent variable (sometimes called an outcome variable) is one that you think is related to the independent variables. Although regression can’t prove causation, you usually think that the relationship goes *from* the independent variable(s) and *to* the dependent variable. (I will discuss the distinction in another post).

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**What are sensitivity and specificity?**

Sensitivity and specificity are measures of the effectiveness of a diagnostic test. Most often they are used as part of medical research when doctors (or others) try to determine if a patient has a disease or not. This leads to four possible results: Read more!