# Implements product-limit (Kaplan-Meier) method

### Description

Implements product-limit (Kaplan-Meier) method for time-to-event data with censoring.

### Usage

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### Arguments

`time` |
numeric vector with individual observation times |

`status` |
integer vector indicating status at the end of the observation time: 1 = event, 0 = censored |

### Details

This function implements the product-limit method for estimating survival probability for time-to-event data with censoring:

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where `tj`

are event times (i.e., times at which one or more events
occur), `nj`

are the number at risk at time `tj`

(by convention,
subjects censored at time `tj`

are considered at-risk and included in
`nj`

), and `dj`

are the number of events at time `tj`

.

A primary purpose of this function was to demonstrate the use of
available R functions to implement a simple statistical method. For example,
`kapmeier`

uses `sort`

, `order`

, `duplicated`

,
`tapply`

, `unique`

, `cumprod`

, `cbind`

, and
`dimnames`

. Studying this function carefully helps one understand
and appreciate the utility of R functions to implement simple methods.

For serious survival analysis load the `survival`

package. The
`survfit`

function in this package implements the product-limit method
and much more. See examples.

### Value

Returns an individual-level data frame

### Note

Visit http://medepi.com for the latest.

### Author(s)

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

### References

Selvin S. Statistical Analysis of Epidemiologic Data (Monographs in Epidemiology and Biostatistics, V. 35). Oxford University Press; 3rd edition (May 1, 2004)

### See Also

See also `survfit`

### Examples

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