Sorry, didn't cc this to the list.
-------- Forwarded Message --------
Subject: Re: [R] Strange results : bootrstrp CIs
Date: Sat, 13 Jan 2024 17:37:19 -0500
From: Duncan Murdoch <murdoch.dun...@gmail.com>
To: varin sacha <varinsa...@yahoo.fr>
You can debug things like this by setting options(error = recover). That
will drop into the debugger when the error occurs. Examine t.star, r,
and res[[r]] and you will likely see what the problem was.
My guess is that one of the bootstrap samples had a different selection
of countries, so factor(Country) had different levels, and that would
really mess things up.
You'll need to decide how to handle that: If you are trying to estimate
the coefficient for Italy in a sample that contains no data from Italy,
what should the coefficient be? (This is easier for Bayesians to
handle: we don't need data!)
Duncan
On 13/01/2024 5:22 p.m., varin sacha via R-help wrote:
Dear Duncan,
Dear Ivan,
I really thank you a lot for your response.
So, if I correctly understand your answers the problem is coming from this line:
coef(lm(Score~ Time + factor(Country)),data=data[idx,])
This line should be:
coef(lm(Score~ Time + factor(Country),data=data[idx,]))
If yes, now I get an error message (code here below)! So, it still does not
work.
Error in t.star[r, ] <- res[[r]] :
number of items to replace is not a multiple of replacement length
##########################################
Score=c(345,564,467,675,432,346,476,512,567,543,234,435,654,411,356,658,432,345,432,345,
345,456,543,501)
Country=c("Italy", "Italy", "Italy", "Turkey", "Turkey", "Turkey", "USA", "USA", "USA", "Korea", "Korea", "Korea", "Portugal", "Portugal", "Portugal", "UK", "UK", "UK", "Poland", "Poland", "Poland", "Austria", "Austria", "Austria")
Time=c(1,2,3,1,2,3,1,2,3,1,2,3,1,2,3,1,2,3,1,2,3,1,2,3)
e=data.frame(Score, Country, Time)
library(boot)
func= function(data, idx) {
coef(lm(Score~ Time + factor(Country),data=data[idx,]))
}
B= boot(e, func, R=1000)
boot.ci(B, index=2, type="perc")
#############################################################
Le samedi 13 janvier 2024 à 21:56:58 UTC+1, Ivan Krylov <ikry...@disroot.org> a
écrit :
В Sat, 13 Jan 2024 20:33:47 +0000 (UTC)
varin sacha via R-help <r-help@r-project.org> пишет:
coef(lm(Score~ Time + factor(Country)),data=data[idx,])
Wrong place for the data=... argument. You meant to give it to lm(...),
but in the end it went to coef(...). Without the data=... argument, the
formula passed to lm() picks up the global variables inherited by the
func() closure.
Unfortunately, S3 methods really do have to ignore extra arguments they
don't understand if the class is to be extended, so coef.lm isn't
allowed to complain to you about it.
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