STATS 250 Lecture Notes - Lecture 12: Dependent And Independent Variables, Analysis Of Variance, Pooled Variance
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STATS 250 Full Course Notes
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Re-watch the video for june 4, 2015 (from the beginning) to re-listen to her explaining the conditions for general vs. pool approach. Time to complete test was recorded between men and women. She gave us the basic summary again: qq plot or histogram. Pie and bar charts would be better for categorical variables: the alcohol group took longer on average by about ~14 seconds. Squaring the standard deviations, we get 572 and 145. Since there is a quite difference, we can choose unpooled (general) since one variance is about/more twice the other: (113. 75-99. 87) +/- t* (square root (22. 64^2)/16 + (12. 04^2)/16) where the df=(n1-1),(n2-2) where you use the smaller df. Here both n=16 so you use either one and get a df=15. (113. 75-99. 87) +/- (2. 13) (square root (22. 64^2)/16 + (12. 04^2)/16) Ci tells us the differences between the average completion time between the alcohol groups and the placebo group.
