Everybody conducts studies. When you see babies dropping their sippy cups from their high-chairs over and over again, they're engaging in one of the most consequential experiments of their lives. The object of their investigation? Gravity.
No matter how many times we drop cups, they always fall to the ground. The fact that this experiment can be repeated endlessly and by anyone with the same result is one of the basic principles of any study. No matter how convincing the results of a study might be, if it can't be repeated by peer researchers, that means it can't be validated.
To point this problem out, the Center for Open Science coordinated 270 researchers in a massive project to reproduce the results from 100 published studies in the field of psychology. In 2015, after years of work, the Center reported that more than half of the studies couldn't be repeated because the evidence gathered for them was not as strong as originally claimed.
One of the studies that they tested, for instance, was designed to determine whether men have a harder time distinguishing sexual cues from friendliness. Following the structure of the original study, the Center for Open Science showed test subjects a series of photos of women exhibiting different facial expressions.
While the original study found that, indeed, men were ninnies at nailing the cues, the follow-up test of the study couldn't replicate those results. It isn't clear whether this was because of cultural differences between the first and second studies (one study was conducted in the UK, the other in the USA) or the time elapsed between studies [source: Firger]. Either way, a finding that can't be reproduced isn't one for the ages.