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Repeated Measures ANOVA

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Presentation on theme: "Repeated Measures ANOVA"— Presentation transcript:

1 Repeated Measures ANOVA
Univariate and Multivariate Approaches

2 Setting t Treatments/Conditions to compare
N subjects to be included in study (each subject will receive only one treatment) r subjects receive trt i: tr = N p time periods of data will be obtained Effects of trt, time and trtxtime interaction of primary interest. Between Subject Factor: Treatment Within Subject Factors: Time, TrtxTime

3 Model Note the random error term is actually the interaction between subjects (within treatments) and time

4 Mean & Variance Structure
The second assumption (assuming equal covariances among repeated measures on subjects) is not always realistic and can be tested and adjusted for by multivariate approach.

5 Obtaining Variances of Sums & Means

6 Variances of Other Means

7 Analysis of Variance

8 Expected Values in Analysis of Variance

9 Expected Mean Squares

10 Tests for Fixed Effects

11 Comparing Treatment Means

12 Comparing Time Means

13 Comparing Treatment Means @ 1 Time
Approximate degrees of freedom on next slide

14 Approximate Degrees of Freedom (Satterthwaite)

15 Multivariate Approach
Makes use of Multivariate ANOVA String out each individual’s p measurements into a px1 vector The Variance-Covariance matrix among measurements on the same subject is assumed to have common variances on the main diagonal and common covariances off-diagonal (Compound Symmetry) Huynh-Feldt condition (less rigid):

16 Mauchley Test

17 Adjusted Degrees of Freedom – Within Trt


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