I'm reviewing some meta-analyses on psychotherapies and trying to make sense of the statistics related to heterogeneity, specifically Cochran's Q and the I-squared value.
I'm confused about how to interpret a non-significant Q statistics while the I-squared value is >40%. Reading Cochran advice, anything I-squared value above 40% is potentially problematic but if the Q statistic is not significant then what does that mean in terms of describing whether heterogeneity (a) exists and (b) warranted, for example, carrying out a moderator analysis.
For example, the stats from one meta-analysis are below:
Q(2) = 4.05, p > 0.05, I2 = 50.66
The Q is non-significant but the I-squared is >40%. The authors state that the heterogeneity was "low". While the number of studies is extremely small (n=3) and a moderator analysis not really possible from my reading, how would the heterogeneity in this meta-analysis be best described?