How to read Big Data studies

This is part 3 of my response to Gelman's post about the DST/heart attacks study. The previous parts are here and here. One of the keys of vetting any Big Data/OCCAM study is taking note of the decisions made by the researchers in conducting the analysis. Most of these decisions involve subjective adjustments or unverifiable assumptions. Not that either of those things are inherently bad - indeed, any analysis one comes across is likely to utilize one or more likely both. As consumers of such analyses, we must be aware what the decisions are. The authors selected a period of...