[R-meta] N of trials or participants?

Viechtbauer, Wolfgang (NP) wo||g@ng@v|echtb@uer @end|ng |rom m@@@tr|chtun|ver@|ty@n|
Wed Feb 1 12:42:54 CET 2023

Thanks for clarifying.

So let's say each subject goes through m trials on some task and either correctly identifies a target or not on a given trial. Let x_j denote the number of trials on which the target was correctly identified by the jth subject and so p_j = x_j/m would be the corresponding proportion of trials. It would be unusual that p_j is reported for the N subjects in the study. Typically, one might have the mean proportion (so: sum p_j / N) and the standard deviation of the proportions. If the subjects are actually in two groups/conditions, then one can just compute a standardized mean difference in the usual manner based on the two means and SDs. The number of trials (m) is not relevant for this.


>-----Original Message-----
>From: Patrizio E Tressoldi [mailto:patrizio.tressoldi using unipd.it]
>Sent: Wednesday, 01 February, 2023 8:49
>To: Viechtbauer, Wolfgang (NP); r-sig-meta-analysis using r-project.org
>Subject: Re: [R-meta] N of trials or participants?
>Il 01/02/2023 08:44, Viechtbauer, Wolfgang (NP) wrote:
>> I think you are using 'trials' in a different way than how I interpreted it. I
>understood it as meaning 'studies' (as in 'clinical trials') but you seem to be
>referring to repeated measurements on individual subjects. Can you describe in
>more detail what kind of data you are thinking of?
>Sorry, as trials I mean number of repetitions of the task, e.g., to
>guess or identify a target as in many perceptual or cognitive
>psychological tasks.
>Patrizio E. Tressoldi Ph.D.
>Science of Consciousness Research Group
>Studium Patavinum
>Università di Padova
>Padova - ITALY
>Make war history
>support https://en.emergency.it

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