Experiments are crucial to truly understand human behavior and thought. But, if these experiments are not run properly, faulty conclusions can occur. Several experiments are messed up because of small things that could have been prevented. In order to run a successful experiment, one must remember a few small ways that can insure a close to clear conclusion. Two things that must be accounted for are the placebo and nocebo effects, which can easily be sorted out by introducing a placebo and not tell the participants who is in which group. Another is to make sure that there is both an experimental and a control group. The best way to go about picking the participants for each group is the double-blind method, in which case no one knows who is in which group. Another method that can help insure a valid conclusion is to not let the participants know what you are looking for so that they do not unknowingly taint the outcome of the experiment in any way. Many different things other then those previously stated can ruin the outcome of any experiment, even if the experiment is run flawlessly, the conclusion can always be manipulated, whether by accident or not. Conformation bias is a big one. The instructors of an experiment can "unknowingly" alter their findings so that they match up with what they believed the outcome to be before preforming the experiment. Experiments should be done carefully, otherwise the outcomes to them could be very misleading.