Trimming discards extreme observations; winsorizing caps them. The difference matters for the variance: the winsorized sample still has n observations, so the estimator has a smaller standard error than the trimmed mean at the same alpha.
Details
Formula: replace values below the alpha quantile with it and above the
1 - alpha quantile with that, then take the mean.
References
Dixon, W. J. (1960). Ann Math Statist 31:385-391, where Winsor rule is set out and attributed to him.
Examples
V <- c(1, 2, 3, 4, 5, 6, 7, 8)
Winz(V)
#> $estimate
#> [1] 4.5
#>
#> $lower
#> [1] 1.7
#>
#> $upper
#> [1] 7.3
#>
#> $n_changed
#> [1] 2
#>
#> $n
#> [1] 8
#>
#> $method
#> [1] "Winsorized mean"
#>
#> attr(,"class")
#> [1] "morie_rich_result" "list"
