On Jan 2, 2011, at 11:41 PM, David Crow wrote:
Dear R Community-
Is there a logical variable indicating the presence of a warning or
error
message after executing a command? I’m bootstrapping a logit model
(1,000
iterations, relevant code posted below), but the model fails to
converge on
many iterations. (I’m guessing that a small sample size and the
combination
of sampling with replacement, high item missingness, and list-wise
deletion
leads to a sparse data problem for some iterations.)
Even for the iterations that fail to converge, though, the program
produces
parameter estimates. I would like to remove these parameter
estimates from
N x k matrix containing the boostrapped parameter estimates. What I
was
thinking of is adding a line of code to check if there is a warning
or error
message present, recording the iteration numbers where there are
error/warning messages, and replacing the parameters for those
iterations
with NA’s. I’ve checked the help pages for the “warning”,
“getOption”, and
other commands, but it’s not immediately apparent to me how to check
for the
presence of warning or error messages.
?options
#says that if "warn" is >= 2 that warnings are turned into errors
?try
# for handling of errors
--
David.
Here’s the relevant portion of the code (I’ve omitted the parts that
recover
parameter and fit estimates for each iteration):
*************************************
[Code Starts Here]
#Create Objects
N = 1000 #1000 iterations
set.seed(7843)
seed = sample(10000000, 1000)
#1000 Iterations
for (i in 1:N){
#Bootstap (Sampling with Replacement)
set.seed(seed[i])
pre <- subset(cainit, time==1)
sampt1 <- sort(sample(nrow(pre), nrow(pre), replace=T))
sampt1 <- pre[sampt1,]
#T1 Model of Vote Intention
try(T1A <- glm(prop1a ~ educ + age + inc + dem + appgov + appleg +
budget +
co1a +
prop1b + prop1d,family=binomial(link="logit"),
data=sampt1, na.action=na.exclude))
##[NOTE: the “lrm” command is part of the “Design” package]
try(T1a <- lrm(prop1a ~ educ + age + inc + dem + appgov + appleg +
budget +
co1a +
prop1b + prop1d, data=sampt1))
}
[Code Ends Here]
******************************************
The following set of warning/error messages is repeated about a
dozen times
at the end of the loop:
Error in lrm(prop1a ~ educ + age + inc + dem + appgov + appleg +
budget + :
Unable to fit model using “lrm.fit”
In addition: Warning messages:
1: glm.fit: fitted probabilities numerically 0 or 1 occurred
2: glm.fit: fitted probabilities numerically 0 or 1 occurred
3: glm.fit: algorithm did not converge
4: glm.fit: fitted probabilities numerically 0 or 1 occurred
Any help would be greatly appreciated.
Happy New Year!
David
==============================
David Crow
Profesor-Investigador / Assistant Professor
División de Estudios Internacionales
Centro de Investigación y Docencia Económicas
Carretera México-Toluca 3655
Col. Lomas de Santa Fe
01210 México, D.F.
Tel.: (+011 52 55) 5727-9800, ext. 2152
==============================
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David Winsemius, MD
West Hartford, CT
______________________________________________
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PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
