# Convert a data frame of non-equal interval continuous observations into equal interval continuous observations

### Description

`SurvExpand`

convert a data frame of non-equal interval continuous
observations into equal interval continuous observations. This is useful for
creating time-interactions with `tvc`

.

### Usage

1 2 |

### Arguments

`data` |
a data frame. |

`GroupVar` |
a character string naming the unit grouping variable. |

`Time` |
a character string naming the variable with the interval start time. |

`Time2` |
a character string naming the variable with the interval end time. |

`event` |
a character string naming the event variable. Note: must be numeric with 0 indicating no event. |

`PartialData` |
logical indicating whether or not to keep only the expanded data required to find the Cox partial likelihood. |

`messages` |
logical indicating if you want messages returned while the function is working. |

### Details

The function primarily prepares data from the creation of accurate
time-interactions with the `tvc`

command.
Note: the function will work best if your original time intervals are
recorded in whole numbers. It also currently does not support repeated
events data.

### Value

Returns a data frame where observations have been expanded into equally spaced time intervals.

### References

Gandrud, Christopher. 2015. simPH: An R Package for Illustrating Estimates from Cox Proportional Hazard Models Including for Interactive and Nonlinear Effects. Journal of Statistical Software. 65(3)1-20.

### See Also

`tvc`

### Examples

1 2 3 4 5 6 7 8 9 | ```
# Load Golub & Steunenberg (2007) Data
data("GolubEUPData")
# Subset PURELY TO SPEED UP THE EXAMPLE
GolubEUPData <- GolubEUPData[1:500, ]
# Expand data
GolubEUPDataExpand <- SurvExpand(GolubEUPData, GroupVar = 'caseno',
Time = 'begin', Time2 = 'end', event = 'event')
``` |