And we could think, okay, is this a sample study? Is this a sample study? Is this an observational study? Observational, or is this an experiment? Now, a sample study, an experiment, a sample study, you would be trying to estimate a parameter for a broader population. Here, it's not so much that they're estimating the parameter they're trying to see the connection between two variables. And that brings us to observational study because that's what an observational study is all about.