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# I Squared Values

Could anyone inform how JASP calculates the I^2 values in meta-analyses? For example, the Q value in the attached meta-analysis is 5.9 and N is 6. I^2 would be:

=π−(π−1)/π

= (5.9 - 5)/5.9

=15.3

How does JASP Calculate 25.6%?

Thanks!

Ravi

• Hi Ravi,

The relevant blog post mentioned in the help file (https://jasp-stats.org/2017/11/15/meta-analysis-jasp/) says:

"(For instance, Ι2 expresses the excess variance as a percentage of the total variance observed in the effect size estimates across studies, and hence is akin an intraclass correlation; for the other measures, please consult the meta-analysis literature.)"

Google tells me that the definition is  I² = 100% x (Q-df)/Q. So yeah, I don't immediately see how JASP gets the I^2. I'll ask our experts! (and we should really get the help file done)

Cheers,

E.J.

• Thanks!

Ravi