One of my favorite meta-analyses in this vein is the inverted funnel of Doucouliagos and Stanley [1] which investigates elasticity in the employment market. In particular, fractional change in employment &#x2F; fractional change in minimum wage. The idea is that so many studies have been conducted on this topic that if you construct a scatterplot by putting N (study size) on the y axis and elasticity (outcome) on the x axis, then you get a funnel (wide at low-N, narrow at high-N) that can (arguably) reveal selection bias since selection bias will disproportionately affect the wide, low-N side of the funnel.<p>Of course, this technique can only be performed if you have not only large studies, but a large number of studies -- so large that you can resolve an empirical distribution of outcomes at several different N bands. It&#x27;s therefore limited to a small number of topics. Still, it&#x27;s neat to get quantitative insight into an effect that is usually unobservable.<p>[1] pdf page # 33 of <a href="http:&#x2F;&#x2F;citeseerx.ist.psu.edu&#x2F;viewdoc&#x2F;download?doi=10.1.1.398.2297&amp;rep=rep1&amp;type=pdf" rel="nofollow">http:&#x2F;&#x2F;citeseerx.ist.psu.edu&#x2F;viewdoc&#x2F;download?doi=10.1.1.398...</a>