| infert {base} | R Documentation |
Infertility after spontaneous and induced abortion
Description
This is a matched case-control study dating from before the availability of conditional logistic regression.
Usage
data(infert)Format
| 1. | Education | 0 = 0-5 years |
| 1 = 6-11 years | ||
| 2 = 12+ years | ||
| 2. | age | age in years of case |
| 3. | parity | count |
| 4. | number of prior | 0 = 0 |
| induced abortions | 1 = 1 | |
| 2 = 2 or more | ||
| 5. | case status | 1 = case |
| 0 = control | ||
| 6. | number of prior | 0 = 0 |
| spontaneous abortions | 1 = 1 | |
| 2 = 2 or more | ||
| 7. | matched set number | 1-83 |
| 8. | stratum number | 1-63 |
Note
One case with two prior spontaneous abortions and two prior induced abortions is omitted.
Source
Trichopoulos et al. (1976) Br. J. of Obst. and Gynaec. vol.83, pp. 645-650.
Examples
data(infert)
model1 <- glm(case ~ spontaneous+induced, data=infert,family=binomial())
summary(model1)
## adjusted for other potential confounders:
summary(model2 <- glm(case ~ age+parity+education+spontaneous+induced,
data=infert,family=binomial()))
## Really should be analysed by conditional logistic regression
## which is equivalent to a Cox model :
if(require(survival4)){
faketime <- rep(42,nrow(infert))
model3 <- coxph(Surv(faketime,case)~spontaneous+induced+strata(stratum),
data=infert,method="exact")
summary(model3)
detach()# survival4 (conflicts)
}