fert {eha} | R Documentation

## Marital fertility nineteenth century

### Description

Birth intervals for married women with at least one birth, 19th northern Sweden

### Usage

    data(fert)

### Format

A data frame with 12169 observations the lengths (in years) of birth intervals for 1859 married women with at least one birth. The first interval (`parity = 0`) is the interval from marriage to first birth.

`id`

  Personal identification number for mother.

`parity`

  Time order of birth interval for the present mother. The interval with `parity = 0` is the first, from marriage to first birth.

`age`

  The age of mother at start of interval.

`year`

  The calendar year at start of interval.

`next.ivl`

  The length of the coming time interval.

`event`

  An indicator for whether the `next.ivl` ends in a new birth (`event = 1`) or is right censored (`event = 0`). Censoring occurs when the woman ends her fertility period within her first marriage (marriage dissolution or reaching the age of 48).

`prev.ivl`

  The length of the previous time interval. May be used as explanatory variable in a Cox regression of birth intervals.

`ses`

  Socio-economic status, a factor with levels `lower`, `upper`, `farmer`, and `unknown`.

`parish`

  The Skelleftea region consists of three parishes, Jorn, Norsjo, and Skelleftea.

### Details

The data set contain clusters of dependent observations defined by mother's id.

### Source

Data is coming from The Demographic Data Base, Umea University, Umea, Sweden.

### References

http://www.ddb.umu.se

### Examples

    data(fert)
    fit <- coxreg(Surv(next.ivl, event) ~ ses + prev.ivl, data = fert, subset =
    (parity == 1))
    drop1(fit, test = "Chisq")

[Package eha version 2.6.0 Index]