I want to get bootstrap confidence intervals for more than one statistics through boot.ci
function. Here is my MWE.
I've two statistics in out
and want to find the bootstrap confidence intervals for these two statistics. However, boot.ci
function is providing the bootstrap confidence intervals for only first statistic (t1*) but not for the second statistic (t2*).
set.seed(12345)
df <- rnorm(n=10, mean = 0, sd = 1)
Boot.fun <-
function(data, idx) {
data1 <- sample(data[idx], replace=TRUE)
m1 <- mean(data1)
sd1 <- sd(data1)
out <- cbind(m1, sd1)
return(out)
}
Boot.fun(data = df)
library(boot)
boot.out <- boot(df, Boot.fun, R = 20)
boot.out
RDINARY NONPARAMETRIC BOOTSTRAP
Call:
boot(data = df, statistic = Boot.fun, R = 20)
Bootstrap Statistics :
original bias std. error
t1* -0.4815861 0.3190424 0.2309631
t2* 0.9189246 -0.1998455 0.2499412
boot.ci(boot.out=boot.out, conf = 0.95, type = c("norm", "basic", "perc", "bca"))
BOOTSTRAP CONFIDENCE INTERVAL CALCULATIONS
Based on 20 bootstrap replicates
CALL :
boot.ci(boot.out = boot.out, conf = 0.95, type = c("norm", "basic",
"perc", "bca"))
Intervals :
Level Normal Basic
95% (-1.2533, -0.3479 ) (-1.1547, -0.4790 )
Level Percentile BCa
95% (-0.4842, 0.1916 ) (-0.4842, -0.4629 )
Calculations and Intervals on Original Scale
Warning : Basic Intervals used Extreme Quantiles
Some basic intervals may be unstable
Warning : Percentile Intervals used Extreme Quantiles
Some percentile intervals may be unstable
Warning : BCa Intervals used Extreme Quantiles
Some BCa intervals may be unstable
Warning messages:
1: In norm.inter(t, (1 + c(conf, -conf))/2) :
extreme order statistics used as endpoints
2: In norm.inter(t, alpha) : extreme order statistics used as endpoints
3: In norm.inter(t, adj.alpha) :
extreme order statistics used as endpoints