fit_model

Fit parametric model for selected subjects

internal

Implements tipping point sensitivity analysis for time-to-event endpoints under different missing data scenarios, as described in Oodally et al. (2025) <doi:10.48550/arXiv.2506.19988>. Supports both model-based and model-free imputation, multiple imputation workflows, plausibility assessment and visualizations. Enables robust assessment for regulatory and exploratory analyses.

Ajmal Oodally

tipse

Tipping Point Analysis for Survival Endpoints

Craig Wang

Zheng Li

fit_model function

<dl><dt>dat</dt>
<dd>data.frame containing at least 5 columns: TRT01P (treatment arm as factor), AVAL (survival time), EVENT (event indicator), CNSRRS (censoring reason) and MAXAVAL (maximum potential survival time, duration between randomization to data cut-off)</dd>
<dt>reason</dt>
<dd>a string specifying the censoring reasons which require imputation. It must be one of the reasons from column CNSRRS.</dd>
<dt>impute</dt>
<dd>a string specifying the treatment arm(s) which require imputation. It must be one of the arms from column TRT01P.</dd>
<dt>imputation_model</dt>
<dd>a string specifying the parametric distribution used for imputation, can be "Weibull" or "exponential".</dd></dl>

Arguments

Fit parametric model for selected subjects — fit_model

<dl>

<dt>dat</dt>
<dd>data.frame containing at least 5 columns: TRT01P (treatment arm as factor), AVAL (survival time), EVENT (event indicator), CNSRRS (censoring reason) and MAXAVAL (maximum potential survival time, duration between randomization to data cut-off)</dd>


<dt>reason</dt>
<dd>a string specifying the censoring reasons which require imputation. It must be one of the reasons from column CNSRRS.</dd>


<dt>impute</dt>
<dd>a string specifying the treatment arm(s) which require imputation. It must be one of the arms from column TRT01P.</dd>


<dt>imputation_model</dt>
<dd>a string specifying the parametric distribution used for imputation, can be "Weibull" or "exponential".</dd>

</dl>

AVAL4	Placeholder column to keep imputed survival times
EVENT4	Placeholder column to keep imputed events
impute	Flag indicating whether the subject was selected for imputation
a	Shape parameter, equal to 1 if exponential
b	Scale parameter
cdf	Cumulative distribution function
...	Some temporary columns

fit_model: Fit parametric model for selected subjects

Description

Usage

Value

Arguments

Details