One of the most common logical mistakes people make when interpreting research findings they read online is to assume a causal relationship based on correlational information. In other words, they read that two things happened at the same time, and they assume that one must be CAUSING the other. That's not always true.
A silly, but illuminating, example is the correlation between Pirates and Climate Change. You can easily chart the disappearance of Pirates from the seas along with the increase in Climate Change, and create a beautiful (and misleading) pattern. It's definitely true that Climate Change has dramatically increased over time, and that Pirates have dramatically decreased over that same time period. Does this mean that a solution for the problems of Climate Change is to bring back the Pirates? Obviously not. Both of these variables have their own causes, and they're simply not causally related to each other (one did not cause the other).
A related mistake occurs when people misunderstand the Direction of Causality. For example, there's a causal relationship between roosters crowing and the sun coming up. But it would be wrong to assume that the rooster's crow CAUSES the sun to come up. Instead, the Direction of Causality goes the other way; the sun coming up causes the rooster to crow.
But often we don't really know which direction the correlational link goes. Take a recent study on the use of Facebook, for example. In it, the researchers followed 5,000 subjects for 2 years, checking in with them regularly to measure their mood and emotional state. Their results indicated a strong CORRELATION between 1) amount of time spent each day on Facebook, and 2) overall well-being. In other words, it seemed that the more time you spend on Facebook, the worse you feel. But wait a minute! This is a correlational study! Isn't it also possible (and logical) that people who feel worse are more likely to use Facebook? Facebook is a convenient way for people to connect with their friends and followers. It makes sense to me that, when people are feeling down, they reach out on social media and thus spend more time on sites like Facebook. This Direction of Causality issue was completely lost on most people reporting the study, and thus the majority of people (who will never read the original study) will come away with a very different conclusion than the data actually suggest.
