Dear R experts,
I would like to get an R^2 - like value for a multilevel regression using lme.
I followed an archived suggestion by José
Pinheiro to use the squared correlation between
fitted and observed values, i.e.,
(cor(fitted(model.lme), getResponse(model.lme))^2
but getResponse returns the error message
Error in val[, level] : incorrect number of dimensions
The same happens with residuals(model.lme) and
summary(model.lme) but not other generic
functions such as predict, coef, or fitted, which (seem to) work fine.
I have searched the archives but could not find a
solution--I don't really understand what dimensions R is referring to.
Any comments or suggestions would be greatly appreciated!
Thanks for your time, and happy new year,
Ullrich
Below is part of the dataframe and the code:
> WMUCTrim
Subj Cond Acc S R T
1 1 1 0.6666667 1 1 1
2 1 2 0.8095238 1 0 1
4 1 4 1.0000000 1 0 0
6 1 6 0.9523810 0 0 1
7 1 7 0.8571429 0 1 0
8 1 8 1.0000000 0 0 0
209 2 1 0.3809524 1 1 1
210 2 2 0.9047619 1 0 1
212 2 4 1.0000000 1 0 0
214 2 6 0.8571429 0 0 1
215 2 7 0.6666667 0 1 0
216 2 8 1.0000000 0 0 0
> mlr2 <- summary(lme(Acc ~ R + T + S, random = ~1 | Subj))
> mlr2
Linear mixed-effects model fit by REML
Data: NULL
AIC BIC logLik
-1140.414 -1113.778 576.2068
Random effects:
Formula: ~1 | Subj
(Intercept) Residual
StdDev: 0.07069723 0.08233792
Fixed effects: Acc ~ R + T + S
Value Std.Error DF t-value p-value
(Intercept) 0.9843537 0.008937809 522 110.13367 0.0000
R1 -0.1139456 0.006958824 522 -16.37426 0.0000
T1 -0.1012472 0.006958824 522 -14.54946 0.0000
S1 -0.0137188 0.006958824 522 -1.97143 0.0492
Correlation:
(Intr) R1 T1
R1 -0.260
T1 -0.260 0.000
S1 -0.260 0.000 -0.333
Standardized Within-Group Residuals:
Min Q1 Med Q3 Max
-4.21190127 -0.46318153 0.02715579 0.58591808 2.57708969
Number of Observations: 630
Number of Groups: 105
> class(mlr2)
[1] "summary.lme" "lme"
> cor(fitted(mlr2), getResponse(mlr2))^2
Error in val[, level] : incorrect number of dimensions
Dr Ullrich Ecker | Postdoctoral Research Fellow |
Cognitive Science Laboratories | Room 211 Sanders Building |
* School of Psychology | M304 | The University of
Western Australia | 35 Stirling Highway | Crawley WA 6009 | Australia |
( 08 6488 3266 | Ê 08 6488 1006 | À 04 5822 0072
| @ ullrich.ec...@uwa.edu.au | i www.cogsciwa.com |
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