Imagine that you have access to a collection of studies in which an age range, a sample size and an "effect" (say, cigarettes per day) is reported. What is the best way to construct a meta-regression of cigarettes per day by age?
The hard part here is to correctly interpolate across these studies with different sample sizes and different age ranges. First, the distribution of ages won't be reported. Second, I only have the effect mean and variance for the entire study. In the limit, it seems reasonable that enough studies with enough age ranges will give me an appropriate estimate of the relationship between age and cigarettes per day. Do you know if this sort of analysis has been done before, and if the appropriate statistical tests have been derived?