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Stat 322 – Day 14. ANOVA and Multiple Comparisons. Announcements. No Tuesday 12-1 office hour this week HW 4 posted online, due Friday Writing Assignment 4 posted with HW 4, due Monday Tuesday 11-12 talk, Science North Room 201
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Stat 322 – Day 14 ANOVA and Multiple Comparisons
Announcements • No Tuesday 12-1 office hour this week • HW 4 posted online, due Friday • Writing Assignment 4 posted with HW 4, due Monday • Tuesday 11-12 talk, Science North Room 201 • Cost-Sensitive Boosting: An Estimation Procedure when the Average is not the ‘Gold Standard’ • Brian Kriegler, UCLA • Writing Assignment….
Previously • When want to compare several population means (or treatment means), can use Analysis of Variance • H0: m1 = … = mI • Ha: not all miequal • Compare variability in sample means, MSTr, to (pooled) variability within groups, MSE • F = MSTr/MSE with df I-1 and N-I • Is it large?
Handicap Discrimination • Minitab • ANOVA table • MS = SS/df One-way ANOVA: SCORE versus HANDICAP Source DF SS MS F P HANDICAP 4 30.52 7.63 2.86 0.030 Error 65 173.32 2.67 Total 69 203.84
Technical conditions • Normal populations • Normal probability plot for each sample • Equal variances in the populations • Largest SD / smallest SD < 2 • Independent observations • Random samples or randomized experiment
Example 2: Chip melting • H0: mwhite = msemi-sweet = mbutterscotch • Ha: not all mi equal
Next Question: • If do reject H0, how can we decide which group means differ significantly from each other
Multiple Comparison Procedures • How compare?