I am performing a meta-analysis (with 'metafor' R-project) as described by Becker (1988), and I compute the standardized mean change for a treatment and control group.

I compute a (standardized) effect size measure for pretest posttest control group designs, where the characteristic, response, or dependent variable assessed in the individual studies is a quantitative variable (Morris 2008).

See link: http://www.metafor-project.org/doku.php/analyses:morris2008?s[

Now, two new articles are published recently with only the posttests.

Question: can SMDs still be calculated with only the posttest (and sd) of treatment and control groups?

Thank you in advance, Roberto


1 Answer 1


No, it isn't possible, at least not without some assuming that the two groups were indistinguishable at baseline and also assuming some distribution for the scores at baseline, these are very big assumptions.


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