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A comparison of three different methods to calculate
the potential impact fraction of an intervention. See the example spreadsheet in the download for details.
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Description
An important measure of effect on the population level,
used to calculate the impact on risk for disease, given a risk factor intervention, is the potential impact fraction (PIF). The PIF is mostly calculated using a categorical risk factor distribution and a
relative risk for each category. However, some risk factors, such as hypertension and BMI, are much better described by continuous distributions.
When a PIF is calculated from a continuous risk
factor distribution, it is necessary to calculate the integral of the product of the risk factor distribution and the corresponding relative risk function (see the paper in the download for details). The
risk factor integral add-in provides this functionality for Excel.
Several risk factor distributions and risk functions are available. A basic understanding of integration will be helpful to set
correct integration boundaries.
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Features
Fast, compiled code (no VBA!)
Normal, Lognormal, and Weibull risk factor distributions
Linear, Loglinear, Logit, and per unit relative risk functions
High precision numerical integration method (Romberg integration)
Full support for the new Excel 2007 features, including multi-threaded recalculation
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