Long.test {ComparisonSurv} | R Documentation |

## Statistical Inference Methods for Testing After a Specified Time Point

### Description

A function used to produce the results of statistical inference methods for testing the difference after a specified time point.

### Usage

```
Long.test(time,status,group,t0)
```

### Arguments

`time` |
The follow up time for right censored data. |

`status` |
The status indicator, normally 1=event, 0=alive or right censored. |

`group` |
The group indicator for comparison, and the elements of this vector must take either 0 or 1. Normally, 0= control group, 1= treatment group. |

`t0` |
The cut-point time, which should larger than the minimum of non-censored time and also less than the maximum of non-censored time. |

### Value

A list containing the following components:

`method` |
Containing 4 statistical inference methods: partial log-rank, Zols, Zspp, and Chi-square(Qua). See more details in references. |

`t0` |
The prespecified cut-point time. |

`statistic` |
The statistics of corresponding methods. |

`pvalue` |
The test P value of corresponding methods. |

### Note

The partial log-rank method is different from the log-rank method in overall.test. Here, the "partial" means let all observations left truncated at the cut-point time t0.

### References

Logan BR, Klein JP, Zhang M. Comparing Treatments in the Presence of Crossing Survival Curves: An Application to Bone Marrow Transplantation. Biometrics, 2008, 64(3): 733-740.

### See Also

### Examples

```
#get 'Crossdata' from package
data(Crossdata)
data1<-Crossdata
#
#get cross point
crosspoint(data1$time,data1$status,data1$group)
#two survival curves crossing at 1.69 years
#
#get the result after cross point (t0=1.69)
Long.test(data1$time,data1$status,data1$group,t0=1.69)
```

*ComparisonSurv*version 1.1.1 Index]