14b_Ch13_One-Factor_ANOVA_Independent

# 14b_Ch13_One-Factor_ANOVA_Independent - One-Factor Analysis...

This preview shows pages 1–10. Sign up to view the full content.

One-Factor Analysis of Variance Assumptions, ANOVA Table, Effect Size, Post Hoc Tests, t and F for Two Independent Samples Independent Samples Assumptions ANOVA (Independent Samples) 1. Independent observations within each sample Assumptions ANOVA (Independent Samples) 1. Independent observations within each sample 2. The populations from which the sample were drawn must be normal

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
Assumptions ANOVA (Independent Samples) 1. Independent observations within each sample 2. The populations from which the sample were drawn must be normal 3. Homogeneity of Variance — the populations from which the samples are drawn must have equal variances Group 1 Group 2 Group 3 Placebo Tranquilizer Hallucinogen Example . . . Example . . . – (1) alpha level use .05 – (2) numerator (between) df = 2 – (3) denominator (within) df = 15 F critical = 3.68 F observed = 15.42 Reject H 0 (observed is larger than critical) The treatments had significantly different effects
Now let’s look at: – How the results are summarized in a table – How to measure effect size – How to pinpoint which means are different from each other when you have a significant ANOVA Example . . . ANOVA Summary Table Source SS df MS F Between Within Total ANOVA Summary Table Source SS df MS F Between 148 Within Total

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
ANOVA Summary Table Source SS df MS F Between 148 Within 72 Total ANOVA Summary Table Source SS df MS F Between 148 Within 72 Total 220 ANOVA Summary Table Source SS df MS F Between 148 2 Within 72 Total 220 ANOVA Summary Table Source SS df MS F Between 148 2 Within 72 15 Total 220
ANOVA Summary Table Source SS df MS F Between 148 2 Within 72 15 Total 220 17 ANOVA Summary Table Source SS df MS F Between 148 2 Within 72 15 Total 220 17 ÷ ANOVA Summary Table Source SS df MS F Between 148 2 74 Within 72 15 Total 220 17 = ÷ ANOVA Summary Table Source SS df MS F Between 148 2 74 Within 72 15 Total 220 17 ÷

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
ANOVA Summary Table Source SS df MS F Between 148 2 74 Within 72 15 4.8 Total 220 17 = ÷ ANOVA Summary Table Source SS df MS F Between 148 2 74 Within 72 15 4.8 Total 220 17 ANOVA Summary Table Source SS df MS F Between 148 2 74 15.42 Within 72 15 4.8 Total 220 17 = ANOVA Summary Table Source SS df MS F Between 148 2 74 15.42 Within 72 15 4.8 Total 220 17
Effect Size Proportion of variance accounted for = Variability due to treatment Total variability η 2 = SS between SS total Effect Size Proportion of variance accounted for = Variability due to treatment Total variability 2 = SS between SS total Eta Squared 2 = SS between SS total = 148 220 = .67

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
Eta Squared η 2 = SS between SS total = 148 220 = .67 Eta Squared 2 = SS between SS total = 148 220 = .67 67% of the variability between groups is due to the drugs Post Hoc Tests Tukey’s HSD Scheffé
Post Hoc Tests • If we reject H 0 , we know that not all of the means are the same 0 H : 1 μ = 2 = 3 • But we don’t know which means are different Post Hoc Tests Group 1 (Placebo) Group 2 (Tranquilizer) Group 3 (Hallucinogen)

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

### Page1 / 30

14b_Ch13_One-Factor_ANOVA_Independent - One-Factor Analysis...

This preview shows document pages 1 - 10. Sign up to view the full document.

View Full Document
Ask a homework question - tutors are online