Autore della sezione: Danielle J. Navarro and David R. Foxcroft
Statistics in psychology
I hope that the discussion above helped explain why science in general is so focused on statistics. But I am guessing that you have a lot more questions about what role statistics plays in psychology, and specifically why psychology classes always devote so many lectures to stats. So here is my attempt to answer a few of them…
Why does psychology have so much statistics?
To be perfectly honest, there is a few different reasons, some of which are better than others. The most important reason is that psychology is a statistical science. What I mean by that is that the “things” that we study are people. Real, complicated, gloriously messy, infuriatingly perverse people. The “things” of physics include objects like electrons, and while there are all sorts of complexities that arise in physics, electrons do not have minds of their own. They do not have opinions, they do not differ from each other in weird and arbitrary ways, they do not get bored in the middle of an experiment, and they do not get angry at the experimenter and then deliberately try to sabotage the data set (not that I have ever done that!). At a fundamental level psychology is harder than physics.[1]
Basically, we teach statistics to you as psychologists because you need to be better at stats than physicists. There is actually a saying used sometimes in physics, to the effect that “if your experiment needs statistics, you should have done a better experiment”. They have the luxury of being able to say that because their objects of study are pathetically simple in comparison to the vast mess that confronts social scientists. And it is not just psychology. Most social sciences are desperately reliant on statistics. Not because we are bad experimenters, but because we have picked a harder problem to solve. We teach you stats because you really, really need it.
Can not someone else do the statistics?
To some extent, but not completely. It is true that you do not need to become a fully trained statistician just to do psychology, but you do need to reach a certain level of statistical competence. In my view, there is three reasons that every psychological researcher ought to be able to do basic statistics:
Firstly, there is the fundamental reason: statistics is deeply intertwined with research design. If you want to be good at designing psychological studies, you need to at the very least understand the basics of stats.
Secondly, if you want to be good at the psychological side of the research, then you need to be able to understand the psychological literature, right? But almost every paper in the psychological literature reports the results of statistical analyses. So if you really want to understand the psychology, you need to be able to understand what other people did with their data. And that means understanding a certain amount of statistics.
Thirdly, there is a big practical problem with being dependent on other people to do all your statistics: statistical analysis is expensive. If you ever get bored and want to look up how much the Australian government charges for university fees, you will notice something interesting: statistics is designated as a “national priority” category, and so the fees are much, much lower than for any other area of study. This is because there is a massive shortage of statisticians out there. So, from your perspective as a psychological researcher, the laws of supply and demand are not exactly on your side here! As a result, in almost any real-life situation where you want to do psychological research, the cruel facts will be that you do not have enough money to afford a statistician. So the economics of the situation mean that you have to be pretty self-sufficient.
Note that a lot of these reasons generalise beyond researchers. If you want to be a practicing psychologist and stay on top of the field, it helps to be able to read the scientific literature, which relies pretty heavily on statistics.
I do not care about jobs, research, or clinical work. Do I need statistics?
Okay, now you are just messing with me. Still, I think it should matter to you too. Statistics should matter to you in the same way that statistics should matter to everyone. We live in the 21st century, and data are everywhere. Frankly, given the world in which we live these days, a basic knowledge of statistics is pretty damn close to a survival tool! Which is the topic of the next section.