Analysis of Repeated Measures Data Ramon C. Littell

Effect on growth regulators on chrysanthemum plantsData courtesy James Barrett and Terril NellMixed Model Repeated Measures AnalysesCovariance Matrix from r option in repeated statement:Estimated R Matrix for plt(blk*chem) 1 1 bonziRow Col1 Col2 Col3 Col4 Col5 Col61 0.8681 0.7806 1.6236 3.4014 4.3750 4.17362 0.7806 0.8111 1.5667 3.4639 4.7583 4.64443 1.6236 1.5667 4.5361 10.2403 12.5236 11.87224 3.4014 3.4639 10.2403 27.1181 34.4472 32.99035 4.3750 4.7583 12.5236 34.4472 50.6736 49.31256 4.1736 4.6444 11.8722 32.9903 49.3125 49.5417Interpretation:• The variance of height is .8681 at time 1, .8111 at time 2, 4.536 at time 3, etc.• The covariance is .7806 between heights at times 1 and 2, 1.623 between times 1 and 3,1.566 between times 2 and 3, etc.• General pattern:- variances increase with time- covariances increase with timeCorrelation Matrix from rcorr option in repeated statement:Interpretation:Estimated R Correlation Matrix forplt(blk*chem) 1 1 bonziRow Col1 Col2 Col3 Col4 Col5 Col61 1.0000 0.9302 0.8182 0.7011 0.6596 0.63642 0.9302 1.0000 0.8168 0.7386 0.7422 0.73273 0.8182 0.8168 1.0000 0.9233 0.8260 0.79204 0.7011 0.7386 0.9233 1.0000 0.9293 0.90015 0.6596 0.7422 0.8260 0.9293 1.0000 0.98426 0.6364 0.7327 0.7920 0.9001 0.9842 1.0000• The correlation is .9302 between heights at times 1 and 2, .8182 between times 1 and 3,.8162 between times 2 and 3, etc.• General pattern:- correlations decrease with time interval- correlations of equal time lag are similar