Hi,
     It's kind of weird for me to not see a return() statement in the
function. Maybe try rolling your own, nonparametric bootstraps aren't all
that bad.
i.e.
reps=1000
stat.holder=rep(NA,reps) ###Rep of NA's so you can pick up errors easily
for(count in 1:reps)
{
bootsample=sample(data, n.data.to.compute.from,replace=T)
##Insert code here to compute statistic
stat.holder[count]=computed.statistic
}
   It may be overtly simplistic, but you may find it helpful.
        Thanks,
           Ken

On Fri, Aug 12, 2011 at 10:10 AM, Alex Olssen <alex.olssen@gmail.com> wrote:

> Hi R-help,
>
> I am trying to implement a nonparametric bootstrap to find the
> standard errors of a simple statistics - the ratio of two scalars.  I
> am having difficulty getting boot() to work correctly.  I code a
> function to create the ratio of the relevant scalars. theta(data, i).
> When I call the function for my data and every observation appearing
> once, theta(test, c(1)), I get the correct statistic for my original
> data.  However when I use boot(test, theta, 200) the original
> statistic is incorrect.
>
> My code and data are below.  The code is very short.
>
> Any help will be appreciated.
>
> Cheers,
> Alex
>
> library(boot)
> test <- read.csv("test.csv")
> test.mean <- mean(test)
> test.cov <- cov(test)*87/88 ## use the biased version as I am
> reproducing a result from a book
> test.eigen <- eigen(test.cov)
> theta <- function(data, i) {
>  data <- data * i
>  data.cov <- cov(data)
>  data.eigen <- eigen(data.cov)
>  data.eigen$values[1]/sum(data.eigen$values)
> }
> test.boot <- boot(test, theta, 200)
>
> test
>   mec vec alg ana sta
> 1 77 82 67 67 81
> 2   63  78  80  70  81
> 3   75 73 71 66 81
> 4   55  72  63  70  68
> 5   63 63 65 70 63
> 6   53  61  72  64  73
> 7   51 67 65 65 68
> 8   59  70  68  62  56
> 9   62  60  58  62  70
> 10 64 72 60 62 45
> 11  52  64  60  63  54
> 12  55  67  59  62  44
> 13  50  50  64  55  63
> 14  65  63  58  56  37
> 15  31 55 60 57 73
> 16  60 64 56 54 40
> 17  44  69  53  53  53
> 18  42  69  61  55  45
> 19  62  46  61  57  45
> 20  31 49 62 63 62
> 21 44 61 52 62  46
> 22 49 41 61 49  64
> 23 12 58 61 63  67
> 24  49  53  49  62  47
> 25  54 49 56 47 53
> 26  54  53  46  59  44
> 27  44 56 55 61 36
> 28 18 44 50 57  81
> 29  46  52  65  50  35
> 30 32 45 49 57  64
> 31  30 69 50 52 45
> 32  46  49  53  59  37
> 33  40 27 54 61 61
> 34  31 42 48 54 68
> 35  36  59  51  45  51
> 36  56  40  56  54  35
> 37  46  56  57  49  32
> 38  45  42  55  56  40
> 39  42  60  54  49  33
> 40  40 63 53 54 25
> 41 23 55 59 53  44
> 42  48 48 49 51 37
> 43  41 63 49 46 34
> 44  46  52  53  41  40
> 45  46  61  46  38  41
> 46  40 57 51 52 31
> 47  49  49  45  48  39
> 48  22 58 53 56 41
> 49  35  60  47  54  33
> 50 48 56 49 42  32
> 51  31 57 50 54 34
> 52  17  53  57  43  51
> 53 49 57 47 39  26
> 54  59  50  47  15  46
> 55  37  56  49  28  45
> 56  40  43  48  21  61
> 57  35  35  41  51  50
> 58  38  44  54  47  24
> 59  43  43  38  34  49
> 60  39  46  46  32  43
> 61  62  44  36  22  42
> 62  48  38  41  44  33
> 63  34  42  50  47  29
> 64  18  51  40  56  30
> 65  35  36  46  48  29
> 66  59  53  37  22  19
> 67  41  41  43  30  33
> 68  31  52  37  27  40
> 69  17  51  52  35  31
> 70  34  30  50  47  36
> 71  46  40  47  29  17
> 72  10  46  36  47  39
> 73  46  37  45  15  30
> 74  30  34  43  46  18
> 75  13  51  50  25  31
> 76  49  50  38  23   9
> 77  18  32  31  45  40
> 78   8  42  48  26  40
> 79  23  38  36  48  15
> 80  30  24  43  33  25
> 81   3   9  51  47  40
> 82   7  51  43  17  22
> 83  15  40  43  23  18
> 84  15  38  39  28  17
> 85   5  30  44  36  18
> 86  12  30  32  35  21
> 87   5  26  15  20  20
> 88   0  40  21   9  14
>
> ______________________________________________
> R-help@r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide
> http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>

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