Meta-Analysis: Making your bad results good for fun and profit.

As mentioned in my last post, genome-wide association studies generated many positive "correlations" for genetic loci related to a particular disorder, that could not be consistently replicated.  This should have tipped them off that they were dealing with false positives.  It didn't, though.  They were determined to turn their lemons into lemonade.  They often did this by using meta-analysis.  The idea behind meta-analysis is that you combine the results of numerous studies, effectively increasing your sample size to give you a more accurate big picture of all the results.  I won't say that this approach is never useful in science, but in these instances, it was nothing more than an attempt to get a positive result.  There are two common approaches to using meta-analysis to bolster your negative results.  The first is focusing on a single genetic polymorphism.  Those performing the meta-analysis would focus their attention on a particular genetic locus for a particular disorder using all the published studies (worth noting that there may have been other studies, more likely with a negative result, that didn't get published).  Here is why you are going to create a false positive result: