Scientific Program > Topic 3 > Session 3M >
Presentation 3M1. NHT in Psychology: Throwing the Baby out with the Bath Water?

Michael Granaas (USA)


Presentation Abstract

For several years null hypothesis testing (NHT) has been the dominant form of statistical analysis in psychology. It has also been subject to periodic criticisms from within the field of psychology. In the past decade these occasional criticisms have turned into a more or less steady stream of criticisms and defences of NHT resulting in several journal articles, at least one edited book, and the convening of an American Psychological Association Task Force.

The controversy stems from the practice in psychology of treating the special case of a no effect (nil) hypothesis as the entirety of NHT. This leads to a variety of justifiably criticized problems with the use of NHT, which have lead some to call for an outright ban on NHT in psychology.

The APA Task Force recommendations have lead to some changes in undergraduate and graduate textbooks, (e.g., new/expanded discussions of power and effect size). These recommendations certainly move psychology toward a more appropriate use of statistical procedures generally, but they do not solve the underlying problem of inappropriate NHT.

The solution lies neither in banning NHT nor in relying solely on alternative procedures, but in "reforming" NHT, replacing a-theoretical null hypotheses with theoretically meaningful hypotheses. Such a reform requires that training emphasize parameter estimation and the testing of theoretical models, an approach that exists in some areas of psychology and appears to be common in other sciences.

Psychology students are typically introduced to NHT in a parameter estimation context, but in moving to research designs with two or more conditions they are frequently taught that the null hypothesis is always a test of no effect. The notion of parameter estimation is lost, often forever. A few will be reintroduced to parameter estimation as part of a specialized data-modelling course in graduate school.

I argue that a greater emphasis on parameter estimation and the testing of models is the correct reform for NHT in psychology. Such an emphasis will ensure that the statistical hypothesis being tested matches the substantive hypothesis of interest. I will discuss the changes that are occurring in psychology and propose further changes that are still needed.


Download in Adobe Acrobat format (110 Kb).


Back to top

ICOTS-6, The Sixth International Conference on Teaching Statistics - International Program Committee (IPC) Website.
Copyright © 2001 by the IASE. All rights reserved. This information is subject to change without notice. This page was last modified on July 2, 2002.
For questions or comments, contact the Webmaster, Dagan Ben-Zvi.