Date: Apr 13, 2012 12:22 AM
Author: Peter Tong
Subject: [ap-stat] TPS 4e Test 10A Q1 (MCQ)

Dear all,

Being a new teacher to AP Stats. I was wondering if anyone can help me with this question.

A city planner is comparing traffic patterns at two different intersections. He randomly selects 12 times between 6 am and 10 pm, and he and his assistant count the number of cars passing through each intersection during the 10-minute interval that begins at that time. He plans to test the hypothesis that the mean difference in the number of cars passing through the two intersections during each of those 12 times intervals is 0. Which of the following is appropriate test of the city planner?s hypothesis?

(a) Two-proportion z-test
(b) Two-sample z-test
(c) Matched pairs t-test
(d) Two proportion t-test
(e) Two-sample t-test

The answer given is (c) Matched pairs t-test but many of my students selected (e) Two-sample t-test.

The book's explanation for (c) is;

The ?pairs? are the twelve sets of 10-minute time intervals?one at each intersection. The parameter of interest is the mean difference between the number of cars at each intersection.

My students are saying that it's "different intersection" and also since it's in Chapter 10, it should be Two-sample t-test. How can I further convince my students?

Thanks.

Peter




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