# Helper function for optimize.mse.BW.

### Description

Helper function for optimize.mse.BW.

### Usage

1 |

### Arguments

`data` |
n by 5 matrix. A data matrix where the first column is XL = min(TL, C) where TL is the time of the long term event, C is the censoring time, and the second column is DL =1*(TL<C), the third column is XS = min(TS, C) where TS is the time of the short term event, C is the censoring time, the fourth column is DS =1*(TS<C), and the fifth column is the covariate. These are the data used to calculate the estimated probability. |

`t0` |
the landmark time. |

`tau` |
the residual survival time of interest. |

`h` |
bandwidth |

`folds` |
Number of folds wanted for K-fold cross-validation. Default is 3. |

`reps` |
Number of repitions wanted of K-fold cross-validation. Default is 2. |

### Value

mean of MSE

### Author(s)

Layla Parast

### References

Parast, Layla, Su-Chun Cheng, and Tianxi Cai. Incorporating short-term outcome information to predict long-term survival with discrete markers. Biometrical Journal 53.2 (2011): 294-307.