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Unformatted text preview: Math 127B, Notes for lecture 13 Mrinal Raghupathi Monday, March 14th, 2011 Administrivia Today we will discuss tests of significance. Reminders 1. Homework 7 is due Thursday, 3/17 in recitation. 2. Quiz in recitation over chapter 26 on 3/17. 3. This weeks recitation will be a discussion of problems from chapter 27. 1 Tests for the difference of sample averages. Suppose that we have two populations. We might be interested in measuring the difference between the two populations in terms of a certain parameter. For example we might want to determine whether men earn more than women, whether high-school drop-out rates are higher in Tennessee of Texas, or whether it rains more in morning or the evening. Problems of this type usually involve taking samples from the tow populations and comparing the statistics obtained. We will look at tests of significance for the difference between the average of two samples. These can be applied to percentages as well. The test is based on the z-score for the difference. We might for example conduct a survey in Tennessee and a survey in Kentucky to compare the average SAT scores of high-school students. In TN the score based on a sample of 1,000 students might be 1,240 and in Kentucky the score might...
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