wbysmv {afthd} | R Documentation |

## Posterior multivariate estimates of AFT model with weibull distribution using MCMC.

### Description

Provides estimate of AFT model with weibull distribution using MCMC for multivariable (maximum 5 covariates of column at a time) in high dimensional gene expression data. It also deals covariates with missing values.

### Usage

```
wbysmv(m, n, STime, Event, nc, ni, data)
```

### Arguments

`m` |
Starting column number of covariates of study from high dimensional entered data. |

`n` |
Ending column number of covariates of study from high dimensional entered data. |

`STime` |
name of survival time in data. |

`Event` |
name of event status in data. 0 is for censored and 1 for occurrence of event. |

`nc` |
number of markov chain. |

`ni` |
number of iteration for MCMC. |

`data` |
High dimensional gene expression data that contains event status, survival time and and set of covariates. |

### Details

This function deals covariates (in data) with missing values. Missing value in any column (covariate) is replaced by mean of that particular covariate.
AFT model is log-linear regression model for survival time ` T_{1}`

,` T_{2}`

,..,`T_{n}`

.
i.e.,

`log(T_i)= x_i'\beta +\sigma\epsilon_i ;~\epsilon_i \sim F_\epsilon (.)~which~is~iid `

Where ` F_\epsilon `

is known cdf which is defined on real line.
Here, when baseline distribution is extreme value then T follows weibull distribution.
To make interpretation of regression coefficients simpler, using extreme value distribution with median 0.
So using weibull distribution that leads to AFT model when

` T \sim Weib(\sqrt{\tau},log(2)\exp(-x'\beta \sqrt{\tau})) `

### Value

Data frame is containing mean, sd, n.eff, Rhat and credible intervals for beta's, sigma, alpha, tau and deviance of the model for the chosen covariates. beta[1] is for intercept and others are for covariates (which is/are chosen as columns in data). sigma is the scale parameter of the distribution. alpha is shape parameter of the distribution.

### Author(s)

Atanu Bhattacharjee, Gajendra Kumar Vishwakarma and Pragya Kumari

### References

Prabhash et al(2016) <doi:10.21307/stattrans-2016-046>

### See Also

pvaft, wbysuni, rglwbysm, wbyscrkm, wbyAgmv

### Examples

```
##
data(hdata)
wbysmv(9,13,STime="os",Event="death",2,10,hdata)
##
```

*afthd*version 1.1.0 Index]