How do you calculate PAF?
- Pi = proportion of population at exposure level i, current exposure.
- P'i = proportion of population at exposure level i, counterfactual or ideal level of exposure.
- RR = the relative risk at exposure level i.
- n = the number of exposure levels.
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Similarly one may ask, how do you calculate population etiologic fraction?
Etiologic fraction = [ a / ( a + b ) − c / ( c + d ) ] 1 − [ c / ( c + d ) ] (population attributable risk). The relative risk used by epidemiologists for prospective studies differs slightly from the odds ratio used in case–control studies and is defined as a/(ac)/b(bd).
Also, how do you calculate incidence rate? In contrast, the incidence proportion can be calculated as 16 ⁄ 2,100 = 7.6 cases per 1,000 population during the four-year period, or an average of 1.9 cases per 1,000 per year (7.6 divided by 4 years).
Hereof, what is the formula for the population attributable risk?
Calculating the population attributable risk percent allows you to determine what percent of an outcome could possibly be prevented if a risk factor were to be removed from the population. To calculate the attributable risk, one simply subtracts the risk for the non-exposed group from the risk for the exposed group.
How do you calculate relative risk and attributable risk?
The formula on the right shows that the attributable risk is related to the relative risk, but instead of it being the ratio of the incidence rates, it is the difference between them. Attributable risk is the difference in the probability of disease in exposed people and the probability of disease in unexposed people.