R Help -

Why is that in the results below, changing the order of the factor
(trialType2: levels - DD, SD, DS, SS) changes the estimates in the fixed
effects tests?

> tmp.dat4$trialType2 <- sort(tmp.dat4$trialType, decreasing = TRUE)
> mod2c <- lme(proportion.down ~ trialType2, data = tmp.dat4, random = ~ 1
| subject, na.action = na.omit, method = "ML")
> summary(mod2c)
Linear mixed-effects model fit by maximum likelihood
 Data: tmp.dat4
       AIC      BIC    logLik
  27.92306 48.23003 -7.961531

Random effects:
 Formula: ~1 | subject
        (Intercept)  Residual
StdDev:   0.3800017 0.1530272

Fixed effects: proportion.down ~ trialType2
                  Value  Std.Error  DF   t-value p-value
(Intercept)   0.6788875 0.08613476 141  7.881690  0.0000
trialType2DS  0.0287062 0.11267357 141  0.254773  0.7993
trialType2SD -0.0197194 0.12142018 141 -0.162406  0.8712
trialType2SS -0.0941918 0.12204707 141 -0.771766  0.4415
 Correlation:
             (Intr) trT2DS trT2SD
trialType2DS -0.658
trialType2SD -0.709  0.467
trialType2SS -0.706  0.464  0.571

Standardized Within-Group Residuals:
        Min          Q1         Med          Q3         Max
-3.67176824 -0.22090663  0.08677971  0.14331603  2.86301670

Number of Observations: 218
Number of Groups: 74
> tmp.dat4$trialType2 <- sort(tmp.dat4$trialType, decreasing = FALSE)
> mod2c <- lme(proportion.down ~ trialType2, data = tmp.dat4, random = ~ 1
| subject, na.action = na.omit, method = "ML")
> summary(mod2c)
Linear mixed-effects model fit by maximum likelihood
 Data: tmp.dat4
       AIC      BIC    logLik
  27.92306 48.23003 -7.961531

Random effects:
 Formula: ~1 | subject
        (Intercept)  Residual
StdDev:   0.3800017 0.1530272

Fixed effects: proportion.down ~ trialType2
                 Value  Std.Error  DF  t-value p-value
(Intercept)  0.5846957 0.08646554 141 6.762181  0.0000
trialType2DS 0.0744724 0.11277773 141 0.660347  0.5101
trialType2SD 0.1228981 0.12175741 141 1.009368  0.3145
trialType2SS 0.0941918 0.12204707 141 0.771766  0.4415
 Correlation:
             (Intr) trT2DS trT2SD
trialType2DS -0.660
trialType2SD -0.710  0.469
trialType2SS -0.708  0.468  0.573

Standardized Within-Group Residuals:
        Min          Q1         Med          Q3         Max
-3.67176824 -0.22090663  0.08677971  0.14331603  2.86301670

Number of Observations: 218
Number of Groups: 74

-- 
*Edward H Patzelt | Research Assistant
Psychology | University of Minnesota  | Elliott Hall, 75 East River Road |
Minneapolis, MN 55455
Email: patze003@umn.edu  |
Main: 612.626.0072
|
Mobile: 651.315.3410
| Office: S355
**

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