Below is a graph showing the relative price increases of textbooks to other goods from 1978 - 2010. Textbook prices have increased an average of 6.8% per year over this 32-year period, compared to the CPI, which increased just 3.8% per year over this time. (BTW - If the data started with, say, 1982, the annual increase in the CPI would fall about 1.1 percentage points. The inflation during the late 70s and early 80s was substantial.)
Academics (including me) complain all the time about the increasing number of students who refuse to purchase the textbooks required for their classes. What do we fail to understand about the first law of demand? (Can anyone identify what's incorrect with the definition of the law of demand used by Investopedia in the link above?)
HT: Mark Perry for the graph.