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rstatistics-bootstrap

Write bootstrap output to a file


I'm new to R and am trying to do some bootstrap estimates of standard errors for a large file of frequency data. I have the bootstrap working fine on a single data point, but I can't figure out how to save the output. Ideally, I would like to write only the standard error to a new file.

Here is what I've tried so far:

x = c(1,2,3,4,5,6,7,8,9,10)
samplemean = function(x, d){return(mean(x[d]))}
b = boot(x, samplemean, R=1000)
b
ORDINARY NONPARAMETRIC BOOTSTRAP

Call:
boot(data = x, statistic = samplemean, R = 1000)

Bootstrap Statistics :
    original  bias    std. error
t1*      5.5 -0.0356   0.9145759

Solution

  • You can compute the standard errors using the t (replication) slot in your boot object.

    require(boot)
    
    x <- c(1, 2, 3, 4, 5, 6, 7, 8, 9, 10)
    
    samplemean <- function(x, d) {return(mean(x[d]))}
    
    set.seed(123)
    b <- boot(x,samplemean,R=1000)
    b
    ## Bootstrap Statistics :
    ##     original  bias    std. error
    ## t1*      5.5 -0.0232     0.90887
    
    ## str(b) first...
    apply(b$t, 2, sd)
    ##[1] 0.90887