Den 2015-07-24 kl. 00:33, skrev Dera:
Hi, I have a question about how to use the mlogit package in R to do analysis
of discrete choice survey data. Our survey is about asking people to choose
from different insurance policies(with two attributes of deductible and
premium).
The code I used to fit mixed logit is:
[1] ml <- mlogit.data (mydata, choice="choice", shape = "wide", id =
"individual",
opposite =c ('deductible', 'premium'),varying = 5:10)
[2] ml.w5 <- mlogit (choice~deductible+premium|0, ml, panel = TRUE,
rpar = c(deductible='ln', premium='ln'),
R = 100, halton = NA, print.level=0)
I try to use lognormal because we hope the coefficients for both deductible
and premium are negative. And I use "opposite" in [1] to reverse the sign
because lognormal is always positive.
But I always get the error warning:
"Error in if (abs(x - oldx) < ftol) { : missing value where TRUE/FALSE
needed
In addition: Warning message: In log(start[ln]) : NaNs produced"
I double check the data and am sure there isn't any missing data. And if I
change the lognormal "ln" to "n" or "cn", it will work without any warning.
Does anyone know how to deal with this? Thank you for your help.
I've never used the 'mlogit' package but that error message has likely
nothing to do with missingness in your data.
The error message is pretty clear: for some reason 'if (abs(x - oldx) <
ftol)', which looks like a check for convergence, doesn't evaluate to
TRUE or FALSE as expected. Perhaps due to the warning message about
problems with NaN in the starting values? Have you checked your data?
That warning message is typical for when you try to take logs of a
negative number:
> log(-1)
[1] NaN
Warning message:
In log(-1) : NaNs produced
Unless this helps you identify the problem, we need a (preferably small)
reproducible example demonstrating the issue to be able to provide
further help.
BTW, have you asked the package maintainer (as per the posting guide)?
Henric Winell
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______________________________________________
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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.
