[R] boot with strata doubt

[Ernesto Jardim]

Hi,

I'm using the boot package to bootstrap a linear model. The boot command
is:

> blm01 <- boot(mat, boot.fishpower, 1000, strata=boot.strata)

I'm having several problems with the linear model so I decided to check
the stratification. The first thing I did was checking the number of
observations by strata, in particular strata with only 1 observation:

> vec1 <- unlist(lapply(split(boot.strata, boot.strata), length))
> table(vec1)
vec1
 1  2  3  4  5  6  7  8 10 11 12 13 15 21 23 43 56 60
19  3 11  5  4  2  1  1  3  2  1  2  1  2  1  1  1  2

So I have 19 strata with 1 observation. I decided to take a look at the
boot.array matrix to check how many observations where used in all
resamples, I was expecting at least 19. 

> mat2 <- boot.array(blm01)
> vec2 <- apply(mat2,2,FUN=function(x){length(x[x=="1"])})
> vec2[vec2=="1000"]
numeric(0)

This tells me that no observation was used in all resamples.

I am getting something wrong ?

Regards

EJ