PSYC 305 Lecture Notes - Lecture 17: Pearson Product-Moment Correlation Coefficient, Simple Linear Regression, Multiple Comparisons Problem
21 Mar 2017
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As in anova, if we reject h0, then we want to perform post hoc multiple comparison tests to examine which groups differ significantly. Step 1: write down all of the pairwise comparisons we can make. This is about the z-statistic about the w-value (the rank sum of the smaller group) Step 3: any of these tests is significant if its p-value is less than . 05/k. A researcher (welch, purdue univ. ) examined the effect of jumping on the bone density of growing rats. Ten rats were assigned to each of three treatments: a 60- centimeter (cid:498)high jump,(cid:499), a 30-centimeter (cid:498)low jump,(cid:499), and a control group with no jumping. The data file ratbonedensity. sav shows the bone densities of the rats (in milligrams per cubic centimeter) after 8 weeks of 10 jumps per day. H0: the three samples come from the same population. Based on the p-value, we are going to reject the null (comparing three groups)
