Obtaining evidence that something does not exist requires knowing how big it would be
were it to exist. Testing a theory that predicts an effect thus entails specifying the range of …

Psychologists must be able to test both for the presence of an effect and for the absence of
an effect. In addition to testing against zero, researchers can use the two one-sided tests …

Chow (1991) distinguishes betweenpractical impact'andconceptual rigor'research, and he
concludes that effect-size estimation is useful only in practical impact research. I argue that …

In a recent article, Jacob Cohen (December 1994) suggested that the typical way in which
research in the social–behavioral sciences is evaluated (null hypothesis testing) is at best …

Psychological Science recently announced changes to its publication guidelines (Eich, in
press). Among these are many positive changes that will increase the quality of the scientific …

In a recent article, Killeen (2005a) proposed an alternative to traditional null-hypothesis
significance testing (NHST). This alternative test is based on the statistic prep, which is the …

Traditional null hypothesis significance testing does not yield the probability of the null or its
alternative and, therefore, cannot logically ground scientific decisions. The decision theory …

This chapter examines the role of measures of effect magnitude in psychological research.
Measures of effect magnitude fall into one of three categories as shown in Table 5.1. The …

Traditional Null Hypothesis Testing procedures are poorly adapted to theory testing. The
methodology can mislead researchers in several ways, including:(a) a lack of power can …

Despite publication of many well‐argued critiques of null hypothesis testing (NHT).
behavioral science researchers continue to rely heavily on this set of practices. Although we …