According to survey researchers in The Journal of Management, married people who have sexual intercourse at night have increase work performance at their offices the next day. This may or may not be true because the research is based on self-reports (in this case 2 week daily diaries) and when all you have is what people say there’s no way–absolutely no way!–to know if what is said is correct or incorrect. All that can be concluded from these diaries is that people who say they had sexual intercourse at night also say they had increased work performance the following day. And as everyone knows, what people say may, or may not, correspond to what they actually do. Soooo, if you want to find out what’s really going on in the bedroom, office, or anywhere else, DON’T ASK. That’s the theme of my book, The Problem with Survey Research, in which I also discuss in Part Six proper methods of data collection and proper research designs, such as observation, experiments, and so on.
See also my post: Survey Research and Sex.