Why does my research methods textbook have no entry for “effect size”?

Because it’s a bad textbook!

Most textbooks are about 20-30 years behind the state of the methodological art. Prior to writing The Essential Guide to Effect Sizes I scanned more than 30 texts published between 2000 and 2009. I found that 9 out of 10 had nothing to say about effect sizes. If effect sizes were mentioned, it was only in passing.

This will change. In the future textbooks will increasingly show students how to: estimate the magnitude of observed effects, gauge the power of the statistical tests used to detect effects, and interpret effect size estimates in meaningful ways.

This entry was posted on Monday, May 31st, 2010 at 2:18 am and is filed under effect size. You can follow any responses to this entry through the RSS 2.0 feed.
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“The primary product of a research inquiry is one or more measures of effect size, not p values.”
~ Jacob Cohen

How to manuals

“Statistical significance is the least interesting thing about the results. You should describe the results in terms of measures of magnitude – not just, does a treatment affect people, but how much does it affect them.”
~ Gene Glass