### TEACHING TIP: WHAT I DO ON THE FIRST DAY OF STATISTICS CLASS

Beth L. Chance
University of the Pacific

Newsletter for the Section on Statistical Education
Volume 4, Number 1 (Winter 1998)

When I first walk into my Introductory Statistics courses, I have two main goals: give the students a flavor for the course and introduce them to the practice of statistics through examples. I don't feel giving a simple definition of "statistics" is meaningful, and instead want them to discover what the subject involves through recent examples of uses and misuses. I also want them to know from the beginning that this course won't be only about number crunching, but will also emphasize reading numerical discussions, writing technical arguments, and reasoning statistically. To accomplish these goals, first I present a series of myths to the students and then we discuss some more realistic viewpoints of the course. Then I present a series of misuses, mostly from the news. By having students identify the errors in the arguments, they begin to develop their own statistical intuition and understanding of statistical practice. Finally, to ensure they believe that not all statistics are lies I present examples of a few effective uses.

Examples of Myths Students Have Entering the Course

To give students an idea of what I will expect from them in the course, I discuss a series of myths they may hold entering the course:

1. Statistics is a math course.
2. It's completely impossible for me to get a good grade for this course.
3. This course will be a cakewalk.
4. I can continue to cram for an exam the night before.
5. Statistics is memorizing formulas.
6. There is usually only one right answer.
7. The teacher is going to physically harm me if I ask a stupid question.
8. Statistics is not interesting and I will never use it.

I try to emphasize to the students that since computers can now do the numerical calculations so well, our role in studying statistics has changed to being able to tell the computer the right thing to do and then interpreting the output. I also stress that students will need to be able to justify their answers since multiple interpretations are quite possible. (A good example here is two different newspaper headlines based on the same study with opposite implications.) I also try to convey that statistics will not only be important no matter what career they choose, but also just for evaluating information in the newspaper. To study the material, I encourage them to approach it like a foreign language: immersing themselves in the use of the terms, and constantly practicing "talking statistics" with other students. Also, since the students taking my course are so diverse, I encourage them to work with others to share their distinct perspectives. Finally, I tell them my first goal of the course is for them to examine statistics with a critical eye (instead of accepting whatever numbers they hear) and to become intelligent consumers of statistical arguments.

Examples of (Mis)uses of Statistics

I present the following points on overheads and have the class explain to me how they feel about the statements - if they feel they are effective uses of information and convincing arguments. Most of these examples are borrowed from Chapter 3, Section 4 of Statistics: Concepts and Controversies by David Moore, 3rd edition. Moore has an excellent discussion of how to "look at data intelligently". I also try to accompany these points with recent newspaper headlines illustrating the same misuses.

1. True cigarettes have 5 milligrams less tar.
2. Anacin contains more of the ingredient doctors recommend most./Doctors specify Bufferin the most over other leading brands.
3. Dr. Bragg claims his patients have 50% fewer cavities.
4. GM advertises that JD Power picks the Lumina Coupe as the most trouble-free car in its class.
5. Science (1976): People over 65, now numbering 10 million, will number 30 million by the year 2000, and will constitute an unprecedented 25 percent of the population.
6. Dr. Fudge took measurements for 20 animals, recording the number of successful trials. He reported percentages of 53, 58, 63, 46, 48, and 67.
7. The Alabama Development Office reports that the state has attracted 422,657 new industrial jobs in the past 25 years.
8. The unemployment rate is 7.1%.
9. In 1989, 5326 drivers 65 years of age and over were involved in fatal accidents. In contrast, only 2900 drivers aged 16 and 17 had fatal accidents. Thus, young people are safer drivers.
10. South Dakota has the highest average SAT score.
11. The Investment Company Institute claims a \$10,000 investment in 1950 in an average common stock mutual fund would have increased to \$113,500 by the end of 1972.
12. Schick Super chromium razor blades commercial: A group of barbers shave with the same blade, one after the other. The 12th, 13th, 15th, and 17th men to use the blade were interviewed and said the shave was satisfactory.

Discussing this list enables students to develop a list of questions to ask when evaluating any numerical argument: What comparisons are being made? Is the information complete? Are the numbers plausible? Are the definitions clear? Are the right numbers being looked at? What is the source of the information? How was the sample selected? Does the conclusion follow? Are the generalizations valid? I remind them how even the experts have made some serious mistakes (Challenger Accident, Dewey Defeats Truman) and such misuses of statistics should not be taken lightly. Good Uses of Statistics To reassure the students that there are plenty of good uses of statistics, I cite some recent studies that are quite informative. I also share some projects I've been involved with (motivated by Bentley, D. (1994), "My First Day's Lectures: Past and Present" presented at Joint Statistical Meetings) to show them how accessible the questions are to them and the broad variability of disciplines asking the questions. For example, I tell students about my recent work with projects involving

1. A NCAA survey on UOP student interests
2. Availability of pharmacists, with and without principal care providers (with a Pharmacy professor)
3. How are housing prices affected by proximity to toxic waste sites (with a Business School professor)?
4. Does a visual, interactive explanation of statistical concepts improve student learning? (with R. delMas, J. Garfield, U Minn.)
5. How to decide which books should be ordered for the university library (with Library Sciences faculty)
6. Identifying age and motivation when students choose their college major (with Engineering faculty)

I have found these ideas effective at motivating student interest in the course from day one, as well as aligning their expectations of the course with my own. These ideas are reinforced by their first homework, to identify and evaluate uses of statistics in "the news", and throughout the course.

Beth Chance
University of the Pacific
Stockton, CA 95211
(209) 946-3030
bchance@uop.edu