# Weighted log-rank test

### Description

Computes a two sample weighted log-rank statistic with events weighted according to one of the available weighting function choices

### Usage

1 2 |

### Arguments

`formula` |
a formula of the form |

`data` |
a dataframe |

`WtFun` |
a selection from the available list: “FH” (Fleming-Harrington),
“SFH” (stopped Fleming-Harrington) or “Ramp”. See |

`param` |
Weight function parameters. Length and interpretation depends upon
the selected value of |

`sided` |
One or Two sided test? Set to 1 or 2 |

`subset` |
Analysis can be applied to a subset of the dataframe based upon a logical expression in its variables |

`na.action` |
Method for handling |

`w` |
currently no effect |

### Value

An object of class `survtest`

containing components

`pn` |
sample size |

`wttyp` |
internal representation of the |

`par` |
internal representation of the |

`time` |
unique times of events accross all arms |

`nrisk` |
number at risk accross all arms at each event time |

`nrisk1` |
Number at risk in the experimental arm at each event time |

`nevent` |
Number of events accross all arms at each event time |

`nevent1` |
Number of events in the experimental arm at each event time |

`wt` |
Values of the weight function at each event time |

`pntimes` |
Number of event times |

`stat` |
The un-normalized weighted log-rank statistic, i.e. the summed weighted observed minus expected differences at each event time |

`var` |
Variance estimate for the above |

`UQt` |
Cumulative sum of increments in the sum resulting in |

`varQt` |
Cumulative sum of increments in the sum resulting in |

`var1t` |
Cumulative sum of increments in the sum resulting in the variance of an unweighted version of the statistic |

`pu0` |
person units of follow-up time in the control arm |

`pu1` |
person units of follow-up time in the intervention arm |

`n0` |
events in the control arm |

`n1` |
events in the intervention arm |

`n` |
sample size, same as |

`call` |
the call that created the object |

### Author(s)

Grant Izmirlian <izmirlian@nih.gov>

### References

Harrington, D. P. and Fleming, T. R. (1982).
A class of rank test procedures for censored survival data.
*Biometrika*
**69**, 553-566.

### See Also

`IntSurvDiff`

### Examples

1 2 3 |

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