11.2 Calculator regression

Lecture time. Talk about the importance of regression again. Walk them, step-by-step, through a few regressions on the calculator. (Detailed instructions for a TI-83 are included in the“Conceptual Explanations”for this section.)

My advice right now is to look at the points first (which may require resetting the window!) and then categorize them according to concavity—although I don’t use that word. I talk about three kinds of increasing functions:

• Linear functions increase steadily
• Logs and square roots increase more and more slowly
• Parabolas and exponential functions increase more and more quickly

Similarly, of course, for decreasing functions. Choose an appropriate kind of regression, and let the calculator do the rest.

After a few examples, hand out the homework.

Homework

Time for another test!

Question 11c is not something I would put on a real test, for a couple of reasons. First, it would be pretty hard to grade; second, and more importantly, it is unlike anything we’ve seen on a homework. But I might use it for an extra credit, and in any case, it can’t hurt them to see it and discuss it on a sample.