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

[James Pustejovsky]

Hi Emma,

I would advise to carefully inspect your data and computed effect sizes to
determine whether you need to make a further sign-transformation. For my
own projects, I do this by creating tables (in Rmarkdown or by exporting to
Excel) containing the raw summary statistics, direction of effect, and
computed effect size, organized in a way to make it easy to check (e.g., by
sorting the studies on direction of effect). Then I read through the table,
looking for potential inconsistencies.

Even when using very well-validated software, I think this is a good
general habit to build.

Kind Regards,
James

On Tue, Jan 12, 2021 at 8:31 AM Mills, Emma (Student) <
e.mills using lancaster.ac.uk> wrote:

> 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
>  4YF
> Email: e.mills using lancaster.ac.uk; Telephone: +44 794
>  353 5855
> twitter: EmmaMil26429683
>
>
>
> Email too brief? Here's why! http://emailcharter.org
>
>
>
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