Statistical Mistakes and How to Avoid Them
This is the insight that made statistics &quot;click&quot; for me many years ago: a statistical test answers one central question: what are the odds that the results you observed could have arisen by chance?  If those odds are low, then you are justified in concluding that the results probably did not arise by chance, and so there must be some other explanation (usually, but not always, the causal hypothesis you are advancing).<p>Once consequence of this is that it is <i>crucial</i> that you advance your hypothesis <i>before</i> you collect (or at least look at) the data because the odds of something arising by chance change depending on whether you predict or postdict the results.  Also, the more data you have, the more likely you are to find something in there that looks like a signal but is in fact just a coincidence.  Many a day-trading fortune has been lost to this one mistake.