Sunday, May 22, 2005

Mean Absolute Deviation

Today, I tutored a talented young man on some high school statistics. It was about statistics on central tendency and dispersion, in a high school general mathematics book. Several things caught my attention.

1) The use of different terms. All the intro stat books we have examined for our teaching universally use "measure of center" and "measure of spread", not "central tendency" and "dispersion". Andrew once commented that only people for whom English is not a native language will find such usage of the language worthy of noting. Here, I am not fascinated by the differences. In my teaching, I have had a number of students who are confused by the different terms for a same thing in statistics. This is the first time I realize when such "variety" gets started.

2) MAD (mean absolute deviation) was taught. I just quickly checked several intro stat texts we use in this department. None of them cover MAD as a measure of spread. Only one covers a related topic, MAD regression. I can't understand what make such a topic essential to be in a high-school math text but unnecessary in a college intro stat text. Personally, I like MAD.

3) The extensive use of TI-83/84 calculator. It is very foreign to me for a math textbook to illustrate how to use a calculator. Using calculators for homework or exams weren't acceptable when I was in China. The use of calculator has the advantage of enabling the students to work on real-life scale of statistical problems. But following the diagram such as "stats->2->enter->..." In the book, the student, as my pupil said today, "had no idea what he was doing."

This is not an AP stat course. To my understanding, the text used for AP stat is usually very similar to college text but the emphasis is more on the computation not too much on the concepts.


Luis said...

Could you tell what that book is? I am interested in MAD, and as you noted, it is not widely covered in the literature.

Tian Zheng said...

I don't remember. It is a high-school Math-Stat textbook.

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