Using function 'boot on a bi-polar sample'
On Tue, 10 May 2005, Briggs, Meredith M wrote:
I'm not sure I'm using boot correctly:
You are not using argument `i'. Have you read the reference: `boot' is support software for a book? (Or even the definition of `statistic' on the help page?) The bootstrap sample in your case is x[i], not x.
I have a list of values for a variable in BUCKET[, j] I want to use
function 'boot' to estimate a confidence interval on the mean of the
non-zero data. The data can be bi-polar or skewed. Is this the correct
use of boot to establish a mean and standard deviation or median and
percentiles?
x<-BUCKET[, j]
mean.fun<-function(x,i) {mean(x[x>0])}
median.fun<-function(x,i) {median(x[x>0])}
print(mean.fun(x))
print(median.fun(x))
B.mean<-boot(x,mean.fun,R=999)
B.median<-boot(x,mean.fun,R=999)
print(B.mean)
print(B.median)
I need the 'boot' function to sample repeatedly from the density
distribution of the raw data and calculate means, medians etc.
How do I pull out the mean, median, deviations and percentiles into
variables within R?
Brian D. Ripley, ripley at stats.ox.ac.uk Professor of Applied Statistics, http://www.stats.ox.ac.uk/~ripley/ University of Oxford, Tel: +44 1865 272861 (self) 1 South Parks Road, +44 1865 272866 (PA) Oxford OX1 3TG, UK Fax: +44 1865 272595