Calculation of Average Population Attributable Fractions and
Confidence Intervals
Description
Average population attributable fractions are calculated for a set
of risk factors (either binary or ordinal valued) for both prospective and case-
control designs. Confidence intervals are found by Monte Carlo simulation. The
method can be applied to either prospective or case control designs, provided an
estimate of disease prevalence is provided. In addition to an exact calculation
of AF, an approximate calculation, based on randomly sampling permutations has
been implemented to ensure the calculation is computationally tractable when the
number of risk factors is large.