Distinguishing an observational study from an experiment

Intro

Howdy! I'm Professor Curtis of Aspire Mountain Academy here with more statistics homework help.  Today we're going to learn how to distinguish an observational study from an experiment.  Here's our problem statement: Determine whether the description corresponds to an observational study or experiment.  Research is conducted to determine if there is a relation between Parkinson's disease and childhood head trauma.  Does the description correspond to an observational study or an experiment?

Solution

OK, the key difference between an observational study and an experiment is that an observational study is just what the name says.  You're just looking at what's there.  You're just observing.  You're not actually . . . you're not inserting anything, any sort of change, into the variables that you're looking at.  An experiment, on the other hand, requires a treatment.  There's something that you're doing so that you can observe a change in what you're observing here.

The problem statement says that research is being conducted, and a lot of people, when they think about research, they think about that.  Especially when you're dealing with medical things, they associate that with experiments because they're thinking about some sort of drug testing, or we're testing out some sort of procedure to treat the disease.  But in reality here, look at what's actually being said in the statement.  There's nothing in here that says anything about a treatment.  It just says research is conducted.  Well, for all we know, that could mean all we're doing is simply collecting data from people who have Parkinson's disease and seeing which of them had childhood head trauma.  And then we're taking that data and running a statistical analysis to see if there's a correlation between those two variables.  That is actual research that could be conducted.  So we don't know what's going on here.  And there's no indication that there's a treatment going on here.

So this doesn't qualify as an experiment.  This qualifies as an observational study because, again, there is no treatment here.  We're just taking the people who have Parkinson's disease and seeing if they had childhood head trauma.  We're just looking to see what's there.  We're not actually inserting any sort of treatment to observe any sort of change.  Excellent!

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