There is almost no science in studies like this. There are so many variables, that you'd need to collect hundreds of thousands of data points to narrow down the influence on just a couple of variables... and even then, you can't be sure you've found something significant and meaningful. To do science, you need controlled experiments, and these are practically impossible to do with people. Even the well-known psychological "experiments" have been disputed in the recent years [1] [2].

[1]: parapsychology experiments cannot be disproved http://slatestarcodex.com/2014/04/28/the-control-group-is-ou...

[2]: "The Stanford Prison Experiment was flawed" https://news.ycombinator.com/item?id=8073748