# proportional meta-analysis, small confidence intervals and I square of 100 %?

I am performing a meta-analysis of proportions, I have data about the number of cases and the total sample sizes.

I will be using the Freeman-Tukey double arcsine (Freeman & Tukey, 1950; Miller, 1978) to adjust the proportions so that they are between 0.2 and 0.8.

But when I plot data with confidence interval, the confidence intervals are so small and the I square is 100%? what is the problem?

Note: am using R

What you are seeing is entirely consistent. If you have very narrow confidence intervals you will see very high values for $I^2$. In a paper entitles "Undue reliance on $I^2$ in assessing heterogeneity may mislead" available here Rücker and colleagues explain why this is. Basically it is because you are comparing within study and between study variability. If the within is very small then, all else being equal, $I^2$ is bound to be large. Their article is open access by the way.