I am trying to plot the results of a random effects model where each subject is allowed to have his, or her, own intercept. I use xyplot to plot the data, lme to compute the regression and then try to put a summary regression line on the xyplot. As can be seen by the output pasted below, I am getting an error message,
Error in int_abline(a = a, b = b, h = h, v = v, untf = untf, ...) :
?(list) object cannot be coerced to type 'double'
Any ideas what I need to change to make this work?
# Run random effects regression with subject specific slopes.
fitxx<-lme(value~time,random=~1|subject,data=repeatdata,na.action=na.omit)
summary(fitxx)
Linear mixed-effects model fit by REML
?Data: repeatdata
? ? ? AIC ? ? ?BIC ? ?logLik
?303.4246 309.6460 -147.7123
Random effects:
?Formula: ~1 | subject
? ? ? ?(Intercept) Residual
StdDev: ? ?15.17196 9.803319
Fixed effects: value ~ time
? ? ? ? ? ? ? Value Std.Error DF ? t-value p-value
(Intercept) 52.79943 ?4.467854 21 11.817625 ?0.0000
time ? ? ? ?-0.44162 ?0.231605 21 -1.906793 ?0.0703
?Correlation:
? ? (Intr)
time -0.242
Number of Observations: 37
Number of Groups: 15
# Plot data
xyplot(value~time,group=subject,type="b",main="Clot size vs. time.")
# Add summary regression line
abline(fitxx)
Error in int_abline(a = a, b = b, h = h, v = v, untf = untf, ...) :
?(list) object cannot be coerced to type 'double'
John David Sorkin M.D., Ph.D.
Chief, Biostatistics and Informatics
University of Maryland School of Medicine Division of Gerontology
Baltimore VA Medical Center
10 North Greene Street
GRECC (BT/18/GR)
Baltimore, MD 21201-1524
(Phone) 410-605-7119
(Fax) 410-605-7913 (Please call phone number above prior to faxing)
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