In the past year, I've had multiple social scientists tell me that people are the hardest thing to study. Sure, you don't need a Large Hadron Collider. And the chances of suddenly requiring a HAZMAT suit are pretty slim. But people almost never give you the kind of solidly reliable data you can get out of subatomic particles or viruses. The hard part isn't doing the research. The hard part is getting trustworthy, universal answers for anything. If you want to see a good example of those problems in action, check out this great piece on drinking during pregnancy, written by Melinda Moyer.