Correlation does not equal causation and more standard disclaimers.
Below I’ve listed some ‘standard disclaimers’ that should be applied to some of the studies I mention.
Occasionally I mention these in passing, when they are relevant, more often I don’t.
Most of these disclaimers would be introduced to first year psychology students early on in the course.
I don’t like to repeat them every time as it gets repetitive, so here they are in one place.
- Correlation does not equal causation. If a study has a correlational design, you can’t conclude that one thing causes the other. If you see the word survey then it’s probably a correlational study.
- One swallow does not a summer make. One study can’t prove a theory true or, for that matter, prove a theory wrong.
- People are different (I). Psychologists are generally interested in how everybody’s minds work, on average. Individuals can be as unique and different as two snowflakes.
- People are different (II). Lots of studies are done on young, white, middle-class college students. Many people are not white, middle-class college students, or even all that young. Does that mean the results of the studies should be binned? Not necessarily, but it is something to bear in mind.
- It’s the effect size, stupid. Just because a study finds a statistical difference, it doesn’t mean that it makes a real-world difference. Statisticians use something called an ‘effect size’ to quantify this. I almost never mention these.
- They only measured two things. In the simplest studies, scientists measure two things (let’s say happiness and long life), then, after a survey, pronounce a relationship between them. Yes, there could be all kinds of other things going on that weren’t measured, it’s true.