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Repeated Measures ANOVA
Univariate and Multivariate Approaches
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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
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Model Note the random error term is actually the interaction between subjects (within treatments) and time
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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.
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Obtaining Variances of Sums & Means
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Variances of Other Means
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Analysis of Variance
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Expected Values in Analysis of Variance
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Expected Mean Squares
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Tests for Fixed Effects
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Comparing Treatment Means
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Comparing Time Means
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Comparing Treatment Means @ 1 Time
Approximate degrees of freedom on next slide
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Approximate Degrees of Freedom (Satterthwaite)
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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):
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Mauchley Test
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Adjusted Degrees of Freedom – Within Trt
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