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Unformatted text preview: 1 The t-statistic: independent groups (chapter 7) Assumptions for Independent Groups t Test Random selection of participants Independence of Observations Normal population distribution Homogeneity of variance Interval or ratio data Independent Samples t-test Extra Practice Suppose that we plan to conduct a study to alleviate the distress of preschool children who are about to undergo the Fnger-stick procedure for a hematocrit (Hct) determination. Note: Hct = % of volume of a blood sample occupied by cells. 2 Twenty subjects will be used to examine the effectiveness of the special treatment. 10 subjects randomly assigned to treatment group. 10 assigned to a control group that receives no special preparation. Independent Samples t-test Extra Practice Testing hypothesis about two independent means (t-test) Dependent variable = the child s pulse rate just prior to the Fnger-stick Independent variable or grouping variable = treatment conditions (2 levels) Independent Samples t-test...
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- Spring '08