Null Hypothesis

In many sciences, including ecology, medicine, and psychology, null hypothesis significance testing (NHST) is the primary means by which the numbers comprising the data from some experiment are translated into conclusions about the question(s) that the experiment was designed to address. This entry first provides a brief description of NHST, and within the context of NHST, it defines the most common incarnation of a null hypothesis. Second, this entry sketches other less common forms of a null hypothesis. Third, this entry articulates several problems with using null hypothesis-based data analysis procedures.