ility is important, but on its own it’s not enough: After all, I could create a perfectly reliable measurement on a personality test by re-coding every answer using the same number, regardless of how the person actually answers. We want our measurements to also be <em>valid</em> — that is, we want to make sure that we are actually measuring the construct that we think we are measuring (Figure <a href="working-with-data.html#fig:ReliabilityValidity">2.1</a>). There are many different types of validity th