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Aug 16

The pearls of AP Statistics 17

The student law: if you don’t require, they don’t do it.

They say: You have done a regression analysis for the catalog sales company you work for, using monthly data for the last year on y = total sales in the month and x = number of catalogs mailed in preceding month. You are asked to prepare a 200-word summary of what regression does under the heading “Regression for Dummies,” to give to fellow employees who have never taken a statistics course. Write the summary, being careful not to use any technical jargon with which the employees may not be familiar (Agresti and Franklin, p.146).

I say: I am reading Chapter 3 of Agresti and Franklin. The main regression formulas are followed by about 90 exercises (including those in the end of the chapter). None of these exercises requires the reader to reproduce or somehow rearrange equations. However, there are many explanations of how to plug numbers. If the students can plug numbers, why they cannot reproduce the formulas? AP Statistics teachers complain that the students come to their classes with zero Math background. Then why not require them to do at least what they can do?

In my opinion, a textbook should be a staircase: each subsequent chapter should be a bit more difficult than the previous one. And here, 146 pages into the book, the reader is asked to make a report for dummies.

The result is this. When I gave “Applied Econometrics” at a US university, about quarter of my students by the end of the semester could not write down a single equation. Guys, this has to be changed.