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. 83, 645–650.

### Examples

    require(stats)
    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 in the survival package
    if(require(survival)){
      model3 <- clogit(case~spontaneous+induced+strata(stratum),data=infert)
      summary(model3)
      detach()# survival (conflicts)
    }

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