[R] Strange results : bootrstrp CIs

[Duncan Murdoch]

On 13/01/2024 3:33 p.m., varin sacha via R-help wrote:
> 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")

Your function ignores the data, because it passes data[idx,] to coef(), 
not to lm().  coef() ignores it.  So the function is using the global 
variables you created earlier, not the ones in e.

Duncan Murdoch