Estimates the variance of a statistic from its empirical influence values.
var.linear(L, strata = NULL)
Arguments
- L
Vector of the empirical influence values of a statistic. These will usually
be calculated by a call to empinf
.
- strata
A numeric vector or factor specifying which observations (and hence empirical
influence values) come from which strata.
Value
The variance estimate calculated from L
.
References
Davison, A. C. and Hinkley, D. V. (1997) Bootstrap Methods and Their Application. Cambridge University Press.
Examples
# To estimate the variance of the ratio of means for the city data.
ratio <- function(d,w) sum(d$x * w)/sum(d$u * w)
var.linear(empinf(data = city, statistic = ratio))
#> [1] 0.03248701