What constitutes an adjunct?

Over the past few days a new study of Northwestern University by David N. Figlio, Morton O. Shapiro, and Kevin B. Soter and published by the National Bureau of Economic Research has been making the rounds. The study, discussed at The Atlantic, Inside Higher Ed, Orgtheory, and Tenured Radical, among others, finds that students learn more in classes taught by adjuncts than in those taught by tenured or tenure-track faculty. A lot of the people reporting on this study talk about the fact that adjuncts are being paid solely to teach so it may not be surprising that they do a better job of it than those who are also supposed to publish, serve on committees, publish, and publish.

What I have not seen anybody address for certain (and what I have not been willing to pay $5 to access the article to find out myself) is whether the “adjuncts” in the study included graduate students. Beyond the other potential problems with the study (such as using student grades to indicate greater learning), the answer to this question is crucial to interpreting the findings, since graduate students, like tenured and tenure-track faculty (and, as some point out, many adjuncts), also have many other competing expectations and are not just “paid to teach.”

If anybody has access to the full version of the paper I would love to know the answer to this.