Introduction to Psychometrics

Advanced Topics

The content we cover in class is part of what has come to be called traditional or classical test theory. This tradiational approach resembles a lot of other anaylyses conducted via linear regression in that we want to have more data about participants than we have participants. For factor analysis, for example, we typically need dozens or even hundreds of participants per item to generate meaningful results.

However, an other major area of psychometrics has grown along side this approach. Although the ideas in this alternate approach are not new, our abilities to act upon most of them are possible through very large data sets and very computers. Called Item Response Theory (IRT), this approach does not analyze how participants themselves performed, but how the items did.

IRT thus employs many participants who have completed a small set of items.

Additional Resources