Ch24 - Difference between Means We test the hypothesis...

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Chapter 24 Comparing Means
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2 Sample t-Interval for the Difference between Means When the conditions are met, we are ready to find the confidence interval for the difference between means of 2 independent groups, . The confidence interval is where 2 1 μ μ- ) ( SE ) ( 2 _ 1 _ * 2 _ 1 _ y y t y y df - ± - 2 2 2 1 2 1 _ 2 _ 1 ) y y SE( n s n s + = -
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Degrees of Freedom? The degrees of freedom is always at least the smaller of the two n’s minus 1 and at most the sum of the two n’s minus 2. The degrees of freedom that I most commonly use is . 2 n n 2 1 - +
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Actual Degrees of Freedom 2 2 2 2 2 2 1 2 1 1 2 2 2 2 1 2 1 n s 1 n 1 n s 1 n 1 n s n s df - + - + =
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Work on #12 on p. 641
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2 Sample t-Test for the
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Unformatted text preview: Difference between Means We test the hypothesis using the statistic : H 2 1 =- -- -= _ 2 _ 1 _ 2 _ 1 y y SE y y t Standard Error for Hypothesis Testing Unlike the standard error for difference of proportions, the standard error for difference of means is the same as the confidence interval. What about Pooled Data? We can do a pooled t-test for the difference between the means of 2 independent groups but we will not be covering it. Work on #31 on p. 646...
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Ch24 - Difference between Means We test the hypothesis...

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