This study provides a supplemental report of the performance of the confidence interval
for direct standardized rates obtained by the approximate bootstrapmethod (ABC)method.
The ABCmethodwas not considered by theNg et al. (2008) paperwhich compared different
methods of interval construction. A graphical comparison of the coverage probability and
the ratio of the right to left non-coverage probabilities, as a function of the variance in the
weights used for each simulation point, are given for the ABC method, as well as three of
the recommended procedures byNg et al. The expected confidence interval lengths are also
reported. The ABC intervals are shown to be good competitors compared with the other
three confidence intervals.