# Adjunct Faculty and Awful Stats

Via a mailing list, probably via this Tyler Cowen post, an awful statistic about adjunct faculty:

This is awful in two ways. First, it’s obviously a sad comment on the state of the college teaching profession. More importantly, though, it’s a classic abuse of statistics, using a really confusing presentation of the numbers to exaggerate an effect that doesn’t really need it.

Here, let’s try this as a poll, since the way this is stated basically amounts to an eighth-grade algebra word problem. Answer before scrolling down to read the explanation:

(A 10-percentage-point increase here means going from, say, 12% to 22% of the total. Which is not the right answer, by the way.)

SPOILER SPACE

SPOILER SPACE

SPOILER SPACE

SPOILER SPACE

SPOILER SPACE

SPOILER SPACE

SPOILER SPACE

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If you want numbers to make a sensible comparison, you have to solve some equations– if we say that the number of adjunct faculty 35 years ago is x, then the number of tenure-track faculty is 1.44x, and the fraction of adjunct faculty is:

$P(adj) = \frac{x}{x+1.44x} =0.41$

The modern calculation has the number of tenure-track faculty as y and the number of adjuncts as 1.76y, so:

$P(adj) = \frac{1.76 y}{y+1.767} =0.64$

In other words, according to these poorly sourced statistics (I didn’t turn this up on the Chronicle of Higher Ed site or Twitter feed), the adjunct fraction increased from 41% to 64%. It ought to be enough to note that adjuncts have gone from a sizable minority of faculty to a substantial majority, but the “X% more than” formulation is just confusing, in order to sound more scary. Nobody reports numbers this way unless they’re engaged in “How to Lie With Statistics” hackery.

No matter how good the cause, responsible academics should be better than this.

1. #1 Robert
April 25, 2014

Phew…

As a math adjunct, I’m glad I got the answer right. However after having just given a near 8 hour calculus marathon, my brain nearly farted on me and said: “wait, that’s a near quadruple increase (a bit less than half to near double), why is 120% the highest answer?!?”

April 25, 2014

There’s another slightly dodgy aspect of this, namely that it’s “tenured” not “tenure-track.” That might be a slight inaccuracy to keep the original stat tweetable, or it might significantly increase the non-adjunct fraction.

3. #3 Will Smoot
April 25, 2014

Confusing presentation of the numbers, indeed. Unfortunately, the phrasing in the tweet above (and poll) doesn’t lead to the conclusion below. Tenured faculty + adjunct faculty does not equal total faculty.

April 25, 2014

(My comment snuck in while Will’s was in moderation…)

If you add tenure-track but not-(yet)-tenured faculty to the equation, that adds an extra term to the denominator of each of the fractions, which will lower the adjunct percentage in both cases, and tend to bring them closer together. So it is a slight inaccuracy in the conclusion, but only a quantitative issue– the stat used is still confusing in a way that seems to exaggerate the problem.

(Which, I will repeat, is a very real problem, and something that needs to be addressed. But terrible and confusing stats don’t really help with that.)

5. #5 Will Smoot
April 25, 2014

It need not be merely quantitative! A sudden shift in college hiring patterns could have created an assistant professor pool that dwarfs both stated populations. From this data alone, no clear sense if we have 5 % adjunct or 60 % adjunct. Of course, applying logic to the the problem, we can probably assume that those numbers have remained a relatively stable proportion of the total.

April 25, 2014

35 years ago is after the great golden age of faculty expansion and into “In a few years, a wave of retirements will open a lot of tenure-track jobs” so I don’t think there would’ve been a vast number of assistant professors then. Today, as we know, there aren’t a huge number of assistant profs, either. So I think it’s likely to be a fairly small effect on both ends.

April 26, 2014

Having now seen the original figure from which this statistic seems to have been derived– in this tweet, I think “tenured” is short for “tenured and tenure-track.” So the point is moot.

8. #8 CCPhysicist
April 27, 2014

One flaw in those kinds of data is that the number of faculty in one category does not translate into the number of sections or (more importantly) the number of students they teach. At my college there are about 3 times as many adjunct faculty as f-t t-t faculty, but they only teach half of the classes.