R中的自举加权均值 [英] bootstrap weighted mean in R
本文介绍了R中的自举加权均值的处理方法,对大家解决问题具有一定的参考价值,需要的朋友们下面随着小编来一起学习吧!
问题描述
我知道如何引导向量的均值:
I know how to bootstrap the mean of a vector:
library(boot)
samplemean <- function(x, d) {
return(mean(x[d]))
}
results_qsec <- boot(data=mtcars$qsec, statistic = samplemean, R=1000)
但是我如何引导加权平均值,例如考虑值在mtcars$qsec
中,而这些值的权重在mtcars$wt
中?
but how do I bootstrap the weighted mean, considering for instance values are in mtcars$qsec
and weights on these values are in mtcars$wt
?
推荐答案
诀窍是指定weighted.mean
的权重,作为boot
参数的...
参数的一部分.在这里,我使用j
作为权重,并将其作为数据帧传递,以匹配data =
参数.
The trick is to specify the weights for weighted.mean
as part of the ...
argument to boot
. Here I use j
for the weights, and pass it through as a data frame, to match the data =
argument.
您在这里:
samplewmean <- function(d, i, j) {
d <- d[i, ]
w <- j[i, ]
return(weighted.mean(d, w))
}
results_qsec <- boot(data= mtcars[, 7, drop = FALSE],
statistic = samplewmean,
R=10000,
j = mtcars[, 6 , drop = FALSE])
返回:
ORDINARY NONPARAMETRIC BOOTSTRAP
Call:
boot(data = mtcars[, 7, drop = FALSE], statistic = samplewmean,
R = 10000, j = mtcars[, 6, drop = FALSE])
Bootstrap Statistics :
original bias std. error
t1* 17.75677 0.0006948823 0.3046888
比较:
weighted.mean(mtcars[,7], mtcars[,6])
[1] 17.75677
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