p Value

In education disciplines, quantitative studies conducted via statistical hypothesis testing often depend on the calculation of a probability value or p value. Statistical hypothesis testing is a procedure of evaluating suppositions, which are assumptions about certain characteristics of a population, using a sample from that population. The goal of testing a statistical hypothesis is to determine whether the sample evidence challenges the study’s null hypothesis (i.e., there is no observed effect) and supports the alternative hypothesis (i.e., there is an observed effect).

The idea of p value arises in conjunction with the α (or significance) level associated with a statistical test. The α level is the threshold probability value that is chosen for the test; it is commonly .05 or .01 (equivalently, 5% or 1%). The ...