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