[R-meta] Do transformations of omnibus statistical tests show the correct direction of effect in the effect size values?

Mills, Emma (Student) e@m|||@ @end|ng |rom |@nc@@ter@@c@uk
Tue Jan 12 15:30:46 CET 2021

Dear Meta-Analysis Forum

I should be very grateful if you could give me any guidance re the question below.
I've looked back in the archives over the past year but do not see anything that looks like this question.
I am a first time poster, so any other advice for making my posts more effective also greatly appreciated.

The data I have extracted for my meta-analysis includes F-ratio values, p-values, t-test values - where the original papers have omitted means and / or sd values.  Along with those values, I have collected the direction of the effect from the report narrative.  

I have used esc​ / compute.es​ R packages to transform the collected data to either Hedges' g, log(odds) or fisher's z.  

What I am not confident of is that the transformation of omnibus statistic values includes the appropriate direction of the effect, in the way that deriving the effect sizes from means so clearly does.

Should I be confident of the transformation? Or should I multiply the new value by -1 / 1 to ensure the direction of the effect is captured in the individual effect size and then continue with the meta-analysis?

Many thanks in anticipation of your response.  I hope you remain well during these strange times.

Emma Mills


Emma Mills
PhD Student
Psychology Department, Lancaster University, Lancaster, LA1
Email: e.mills using lancaster.ac.uk; Telephone: +44 794
 353 5855
twitter: EmmaMil26429683

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