sasLM (version 0.9.2)

RDinv: Risk Difference between two groups with strata by inverse variance method

Description

Risk difference and its score confidence interval between two groups with stratification by inverse variance method

Usage

RDinv(d0, conf.level=0.95)

Value

The following output will be returned for each strata and common value. There is no standard error.

p1

proportion from the first group, y1/n1

p2

proportion from the second group, y2/n2

RD

risk difference, p1 - p2. Point estimate of common RD is calculated with MH weight.

lower

lower confidence limit of RD

upper

upper confidence limit of RD

Arguments

d0

A data.frame or matrix, of which each row means a strata. This should have four columns named y1, n1, y2, and n2; y1 and y2 for events of each group, n1 and n2 for sample size of each strata. The second group is usually the control group.

conf.level

confidence level

Author

Kyun-Seop Bae [e-mail]

Details

It calculates risk difference and its score confidence interval between two groups. The confidence interval is asymmetric and there is no standard error in the output. If you need percent scale, multiply the output by 100. This supports stratification. This implementation uses nlminb minimization function.

References

Miettinen O, Nurminen M. Comparative analysis of two rates. Stat Med 1985;4:213-26

See Also

RDmn1, RRmn1, ORmn1, RDmn, RRmn, ORmn, RRinv, ORinv, ORcmh

Examples

  d1 = matrix(c(25, 339, 28, 335, 23, 370, 40, 364), nrow=2, byrow=TRUE)
  colnames(d1) =  c("y1", "n1", "y2", "n2")
  RDinv(d1)