[R] trouble with boot ()
Rogério Rosa da Silva
rogeriorosas at gmail.com
Wed May 31 21:27:17 CEST 2006
Dear members,
I am trying to use boot () to compute the distributions of a statistic
of a data set. The statistic is defined in the following code:
eds<-function(x) {
r<-cor(x)
paren<-1-abs(r)/2
denom<-sum(sum(paren)+0.5)
desvio<-sd(x)
media<-mean(x)
a<-desvio/media
nom<-sum(a*(sum(paren)+0.5))
eds_abs<-nom/denom
print(eds_abs)
}
I need to calculate the nonparametric bootstrap confidence intervals for
"eds_abs", but I am confuse about how I should call the second argument
for statistic function (). What I don't understand is where the index
should be set.
I think I need to reproduce in boot () the following
loop:
eds_null <- numeric(1000)
for (i in 1:1000) eds_null[i] <- eds (sample(x,replace=T)),
where "x" is a data matrix (n-by-m) with n rows corresponding to
individual samples, and m-columns corresponding to the different
attributes. For example:
x<-data.frame(var1=c(23,657,67,89,23,657,67,89),var2=c(23,45,67,12,23,657,67,89),
var3=c(25,2009,89,223,23,45,67,12),
var4=c(1299,456,789,2, 23,45,67,12))
> eds(x)
> [1] 6.738244
Thanks for your time,
Rogério
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