A few reasons why these experiments really, really suck
1. Use of Controls (or lack thereof)
A control is an important ingredient in any scientific study. Controls essentially restrict the experiment to test for only a single factor. In each experiment that is said to prove the existence of a parenormal phenomenon, proper controls do not exist.
2. Independant Replication
Experiments that produce results indicating parenormal phenomena are rarely replicated. One of the problems (as with the Rhine experiments) is that intangible factors such as the "freindliness" of the reasearchers is hard to quantify, and therefore replicate.
3. Confounding Factors
Determining causality in an experiement - especially one involving something as complex as human behavior - is a daunting task. Just becuase one event occurs after another event does not mean that the latter caused the former, or that they are in any way related. There is a HUGE level of subjectivity inherent in any of these experiments. This is apparent when dealing with experiments testing for paranormal phenomenon, and there seems to be a correlation between researchers' beliefs regarding the paranormal and the "success" of the experients.
4. Double Blind
A "double blind" experiment is one in which the subject and the researcher are both unaware of the hypothesis of the experiment in which they are participating. This arrangement is very important when conducting studies involving human behavior. If the researcher is aware of the factor being tested for, he may inadvertantly give the subject ques as to what the correct answer is. Similarly, if it is known what the researcher is trying to prove, the subject may unconsciously slant his answers to favor results that support the hypothesis.
