I read a blurb in The Economist about UFO sightings. They charted some 90,000 reports and found that UFO's are, as they put it, "considerate". They tend not to interrupt the work day or sleep. Rather, they tend to be seen far more often in the evening (peaking around 10PM) and more on Friday nights than other nights.
The Economist dubbed the hours of maximum UFO activity to be "drinking hours" and implied that in fact that drinking was the cause of all those sightings.
As researchers, we know that correlation does not mean causation. Of course their analysis is interesting and possibly correct, but it is superficial. One could argue (and I'm sure certain "experts" on the History Channel would) that it is in fact the UFO activity that causes people to want to drink, but by limiting their analysis to two factors (time of day/number of sightings), The Economist ignore other explanations.
For example, the low number of sightings during sleeping hours would make perfect sense (most of us sleep indoors with our eyes closed). The same might be true for the lower number during work hours (many people don't have ready access to a window and those who do are often focused on their computer screen and not the little green men taking soil samples out the window).
As researchers, we need to consider all the possibilities. Questionnaires should be constructed to include questions that help us understand all the factors that drive decision making. Analysis should, where possible, use multivariate techniques so that we can truly measure the impact of one factor over another. Of course, constructing questions that allow respondents to express their thinking is also key...while a long attribute rating battery might seem like it is being "comprehensive" it is more likely mind numbing for the respondent. We of course prefer to use techniques like Max-Diff, Bracket™ or Discrete Choice to figure out what drives behavior.
Hopefully I've given you something to think about tonight when you are sitting on the porch, having a drink and watching the skies.