Recall our cholesterol data displayed in the following table.
Table: Data on blood cholesterol decrease
Man
1
2
3
4
5
6
7
8
9
Decrease
13.75
39.5
-21.0
56.75
10.75
3.25
80.0
41.75
32.5
We wanted to estimate the standard error of the median for which,
unlike the mean, there is no standard error formula.
The bootstrap estimates the standard error of the median by
repeatedly drawing ``bootstrap samples" from the original data,
reevaluating the median for each bootstrap sample, and estimating the
standard error of the original median by the observed variability in
the bootstrap medians.
A bootstrap sample is a sample of the original size, 9 in this
case, drawn randomly but with replacement from the original data set.
Enter a sample size below and watch your web-browser estimate the
standard-error of the median for the above data set. You can do this
as many times as you wish by clicking on the ``Estimate Std. Error''
button.
