The situations that illustrate why a college price index like the UPI might overstate inflation are the ones that involve either unmeasured quality improvements or students changing what/how they buy (substitution and behavior change).

In typical versions of this question, the correct “check all that apply” options are:

  • When quality rises but the index does not fully adjust for it (for example, streaming services or textbooks or energy drinks become much better—extra features, better content, etc.—but the index only sees “higher price,” not “higher quality per dollar”). This creates “quality bias,” so the measured price increase overstates true inflation.
  • When students switch to cheaper or free alternatives as prices go up (for example, textbooks get expensive, so students buy used books or just use the library; or premium streaming gets expensive, so they share accounts instead of subscribing). The index still prices the expensive options in its fixed basket and misses the substitution, so it overstates the actual cost students face.
  • When a new, cheaper alternative for a major item in the basket appears (for example, a cheaper nationwide internet option that many students adopt). If the index keeps using the old, more expensive option, it will overstate how much the cost of college has really risen.

By contrast, options like “professors require each student to buy X notebooks/textbooks regardless of price” or “a memory supplement is developed” do not, by themselves, explain why the index would overstate inflation; they change total spending or are largely irrelevant to how the index is constructed, rather than revealing a bias in the index itself.