8 HP 350 Lecture Slides March 30

8 HP 350 Lecture Slides March 30 - 1 Chapter 14 HP350...

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Unformatted text preview: 1 Chapter 14 HP350 Spring 2010 Midterm #2 Question The p value associated with a statistical test indicates __________ while the associated effect size indicates __________. a. practical importance; statistical significance b. statistical significance; statistical power * c. statistical significance; practical importance d. statistical power; statistical significance 2 3 t vs. F The t test is used to compare two group means. With more than two groups, the F test is used for a comparison of several means. While the t test compares the means , the F test compares the variances. 4 t-test is used to compare two means : H : A = B H 1 : A B F-test is used to compare more than two means : H : A = B = C = H 1 : not H 0 (the means are not equal)-called an Omnibus test (at least one difference between the means) Hypothesis tests for t vs. F 5 Logic of ANOVA The F test is a signal-to-noise ratio that divides up variability in a procedure called analysis of variance , or ANOVA . The analysis of variance provides a comparison of the variation between (signal) the groups and the variation within (noise) the groups. In this kind of analysis, a ratio (the F ratio , or F test ) is formed of and . 2 between S 2 w ith in S 6 F Ratios F ratios usually have values close to 1.0 when the variation between groups is not different from the variation within groups (i.e., when H is true). The larger the F ratio becomes, the greater the dispersion of group means relative to the dispersion of scores within groups. 7 ANOVA Example 8 Descriptives AGE AT FIRST INJECTION 51 16.94 2.626 .368 16.20 17.68 12 23 96 16.42 3.114 .318 15.79 17.05 6 25 96 16.26 3.072 .314 15.64 16.88 8 23 243 16.47 3.000 .192 16.09 16.84 6 25 NY LA NO Total N Mean Std. Deviation Std. Error Lower Bound Upper Bound 95% Confidence Interval for Mean Minimum Maximum...
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This note was uploaded on 06/10/2010 for the course HP 350 taught by Professor Lankenau during the Spring '09 term at USC.

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8 HP 350 Lecture Slides March 30 - 1 Chapter 14 HP350...

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