epitab {epitools}R Documentation

Epidemiologic tabulation for a cohort or case-control study

Description

Calculates risks, risk ratio, odds ratio, and confidence intervals for epidemiologic data

Usage

epitab(..., conf.level = 0.95, trow = FALSE, tcol = FALSE)

Arguments

... four numbers from a 2x2 table (separated by commas), or two vectors (1st vector is exposure variable with r levels, 2nd vector is outcome with 2 levels), or one rx2 contingency table
conf.level Confidence level (default = 0.95)
trow "transpose" (reverse the order of) rows of table
tcol "transpose" (reverse the order of) columns of table

Details

The epitab function can take data in several forms: 4 numbers from cells of a 2x2 table, a nx2 table, or 2 vectors (exposure vs. 2-level outcome). It then calculates the risks for every level, the exposure distribution, Fishers exact p value for every level, the risk ratios with confidence intervals ("cohort analysis"), and the odds ratios with confidence intervals ("case-control analysis"). Therefore, submit either 4 numbers, nx2 table, or 2 categorical vectors. The risk ratios and the odds ratios also include a small sample adjustment (Jewell 2004). The cohort analysis includes the distribution of risk for each level of exposure, and the case-control analysis includes the distribution of exposure for both levels of outcome (case vs. control).

Notice the expected structure of the data to be given to 'epitab':

                 Disease
  Exposure       No (ref)  Yes
   Level 1 (ref)  a         b
   Level 2        c         d

Value

$data Original data in table form, now with marginal totals
$risks Risk for each level
$exposure.distrib Distribution of exposure levels
$cohort.analysis Matrix with risk and risk ratio analysis
$case.control.analysis Matrix with odds ratio analysis

Note

Visit http://www.epitools.net for the latest.

Author(s)

Tomas Aragon, aragon@berkeley.edu, http://www.medepi.net/aragon

References

Jewell NP. Statistics for Epidemiology, 1st Edition, 2004, Chapman & Hall, pp. 73-82

See Also

See also as risk.ratio, odds.ratio

Examples

##Cohort example
##From Jewell (2004), p. 83
risk.ratio(178, 1589, 79, 1565)
epitab(1486, 79, 1411, 178)$cohort

##Case-control example
##From Jewell (2004), p. 79
odds.ratio(347, 555, 20, 88)
epitab(88, 20, 555, 347)$case.control

##Infertility data set in R
data(infert)
epitab(infert$induced, infert$case)$case.control
epitab(cut(infert$age, 2), infert$case)$case.control

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