“than I” or “than me”?

I was just reading through one of the textbooks that we use here at the University of Delaware English Language InstituteBetty Azar‘s mega-best-seller, Understanding and Using English Grammar — when I saw this footnote:

In formal English, a subject pronoun follows than: He’s older than I (am). In everyday informal English, an object pronoun is frequently used after than: He’s older than me.

This made me suspicious for two reasons: “formal” and “everyday informal” English are very vague categories that I don’t find useful; and it seems unlikely to me that this advice holds up in practice.

In fact, it doesn’t. Presumably, by “formal” Azar means academic writing, so I ran a search of the academic section of the Corpus of Contemporary American English. Here’s what I found:

  • than I (28)     than me (37)
  • than he (40)  than him (5)
  • than she (20) than her (5)

(I tried to catch only instances of than I/he/she not followed by a verb — so I don’t include “than I am/say/know/believe/etc.) because the object pronoun is impossible here.)

We can see that: