This tutorial is going to give you a very brief overview of what an experiment really is, just the basics of an experiment. We'll talk about designs in another tutorial. But this is the basics of what an experiment is supposed to be.
An experiment is a different type of study from an observational study. We'll talk about the differences in a second, but the researchers are allowed to impose treatments on the participants. The researcher is able to administer the treatments and then measure the response to those treatments. Conversely, in an observational study, the researcher observes the individuals but does not administer treatment. The researcher just has to allow what would normally happen to happen. And again, they can record variables of interest, but not affect it.
So an experiment is a lot more active on the part of the researcher. Because the researchers are the ones implementing the treatments and measuring the response, you can determine a cause-and-effect relationship between variables. In observational studies you can't, but because the researchers are the ones creating the differences between the two groups, then you can determine a cause-and-effect relationship.
When we talk about experiments, we're going to be using some very common terminology, like subjects and participants. Those are going to be used interchangeably, and the subjects and participants are people involved in an experiment. If we are using animals or things in an experiment, we're going to call them experimental units. That's very universal terminology.
On the occasion that you have a study that you'd like to do but you can't perform it due to ethical concerns or practical concerns, or maybe it takes too much time or it takes too much money, sometimes you can avoid those concerns or get around them by doing an observational study. So for instance, there were several observational studies done with cigarette smoking, but never a true experiment, because that would've been unethical. The same goes for alcohol consumption. And there are all sorts of instances where an experiment would involve privacy issues, when people don't really want to divulge that information. All I have to say is that there are certain times when an observational study is going to be preferred over an experiment.
So to recap, in an experiment, rather than just observing what's going on like in an observational study, the researcher can directly influence the subjects by applying treatments. We talked about an experiment and what all is involved in that, subjects and participants, which are humans, and experimental units, which are animals or things.
Good luck. We'll see you next time.