RelRisk: Relative Risk

Description

Computes the relative risk and it's confidence intervals. Confidence intervals are calculated using normal approximation ("wald"), ("score") or by using oddsratio ("use.or")

Usage

RelRisk(x, y = NULL, conf.level = NA, 
        method = c("score", "wald", "use.or"), delta = 0.5, ...)

Arguments

a numeric vector or a 2x2 numeric matrix, resp. table.

NULL (default) or a vector with compatible dimensions to x. If y is provided, table(x, y, ...) will be calculated.

conf.level

confidence level. Default is NA, meaning no confidence intervals will be reported.

method

method for calculating odds ratio and confidence interval. Can be one out of "score", "wald", "use.or". Default is "score".

delta

small constant to be added to the numerator for calculating the log risk ratio (Wald method). Usual choice is 0.5 although there does not seem to be any theory behind this. (Dewey, M. 2006)

...

further arguments are passed to the function table, allowing i.e. to set useNA.

Value

If conf.level is not NA then the result will be a vector with 3 elements for estimate, lower confidence intervall and upper for the upper one. Else the relative risk will be reported as a single value.

Details

This function expects the following table structure: disease=0 disease=1 exposed=0 (ref) n00 n01 exposed=1 n10 n11 If the table to be provided is not in the preferred form, use the function Rev() to "reverse" the table rows, -columns, or both.

References

Rothman, K. J. and Greenland, S. (1998) Modern Epidemiology. Lippincott-Raven Publishers Rothman, K. J. (2002) Epidemiology: An Introduction. Oxford University Press Jewell, N. P. (2004) Statistics for Epidemiology. 1st Edition, 2004, Chapman & Hall, pp. 73-81 Selvin, S. (1998) Modern Applied Biostatistical Methods Using S-Plus. 1st Edition, Oxford University Press

Examples

Run this code

mm <- cbind(c(9,20),c(41,29))
mm
 
RelRisk(t(mm), conf.level=0.95)
RelRisk(t(mm), conf.level=0.95, method="wald")
RelRisk(t(mm), conf.level=0.95, method="use.or")

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