Okuzeka
Psychology vocabulary · Research Methods and Statistics

Effect size

Meaning in psychology, with examples

nounAdvanced term

In psychology, effect size means: A number that shows how large a difference or relationship is, independent of sample size, such as Cohen's d or a correlation coefficient.

In Turkish: etki büyüklüğü

How it is used

APA style asks authors to report effect sizes alongside significance tests. Cohen's rough guide calls d = 0.2 small, 0.5 medium and 0.8 large. Meta-analyses combine effect sizes from many studies.

Example sentences

  1. The therapy group improved more, with a medium effect size (d = 0.52).

  2. A significant result with a tiny effect size may have little practical importance.

Common collocations

  • report effect sizes
  • small effect size
  • large effect size
  • Cohen's d
  • statistical significanceA sign that a result would be unlikely if there were really no effect, usually judged by whether the p-value falls below a set level such as .05.
  • sampleThe group of people actually studied in research, chosen from a larger population so that the results can, ideally, be generalised to it.
  • correlationA statistical relationship in which two variables change together, in the same direction (positive) or in opposite directions (negative), without showing which causes which.
  • replicateTo repeat a study, usually with new participants, to see whether the original findings appear again; a finding that appears again is also said to replicate.

This word in other fields

The same English word can have a different meaning in another field:

More terms: Research Methods and Statistics

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