Classification: UNCLASSIFIED
Caveats: NONE
Dear R users,
I'm interested in finding a random effect of the Block in the data shown
below, but 'lme' does not work without the random effect. I'm not sure how
to group the data without continuous value which is shown in the error
message at the bottom line. If I use 'aov' with Error(Block), is there a
test method comparing between with and without the Block random effect. I'm
using R 2.4.1.
Appreciate your help.
Kyong
LCU ST1 SURF Block
1 6.71 A N 1
2 6.97 A Y 1
3 6.77 B N 1
4 6.90 B Y 1
5 6.63 C N 1
6 6.94 C Y 1
7 6.79 D N 1
8 6.93 D Y 1
9 6.23 A N 2
10 6.83 A Y 2
11 6.61 B N 2
12 6.86 B Y 2
13 6.51 C N 2
14 6.90 C Y 2
15 5.90 D N 2
16 6.97 D Y 2
A result with the random effect:
Anal1<-lme(LCU~ST1*SURF,random=~1|Block,data=data1)
> summary(Anal1)
Linear mixed-effects model fit by REML
Data: data1
AIC BIC logLik
25.38958 26.18399 -2.694789
Random effects:
Formula: ~1 | Block
(Intercept) Residual
StdDev: 0.1421141 0.218483
Fixed effects: LCU ~ ST1 * SURF
Value Std.Error DF t-value p-value
(Intercept) 6.470 0.1842977 7 35.10625 0.0000
ST1B 0.220 0.2184830 7 1.00694 0.3475
ST1C 0.100 0.2184830 7 0.45770 0.6610
ST1D -0.125 0.2184830 7 -0.57213 0.5851
SURFY 0.430 0.2184830 7 1.96812 0.0897
ST1B:SURFY -0.240 0.3089816 7 -0.77675 0.4627
ST1C:SURFY -0.080 0.3089816 7 -0.25892 0.8031
ST1D:SURFY 0.175 0.3089816 7 0.56638 0.5888
Without the random effect:
Anal2<-lme(LCU~ST1*SURF,data=data1)
Error in getGroups.data.frame(dataMix, groups) :
Invalid formula for groups
Classification: UNCLASSIFIED
Caveats: NONE
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