Treatment effect formula
Nobody has claimed this yet.
Assessment
- Difficulty
- 5/5
- Estimated time
- Over a week
- Newbie friendliness
- 25/100
Research direction
Start by reading pmrm_model_slowing and the current individual model functions to understand how treatment effects are parameterized. Review reformulas as a possible reference for formula processing; done would mean a documented general treatment-formula interface that supports the stated alternative parametrizations and special formula items.
Written by the indexing model from the issue text.
Description
From @larslau:
Idea for a future release: If we enable the use of a formula for specifying treatment effects, we may end up with much richer functionality of
pmrm_model_slowing.Right now, the formula seems to be: ~ arm_active_1_dummy : visit + ... + arm_active_k_dummy : visit + 0.
If the user can specify the formula, it would enable e.g. a proportional slowing model using the same framework (formula: ~ arm_active_1_dummy + ... + arm_active_k_dummy + 0) or other parametrizations, including the same proportional slowing shared over multiple visits, but potentially changing over different trial periods. Or interaction analyses where slowing depends on baseline characteristics.
A general formula interface could replace a lot of the arguments to the current functions:
formula = y ~ spline_slowing(time) + covariates + us(visit | subject_id), treatment_formula = ~ treatment_group : visit + 0where special formula items (e.g. spline_slowing and spline_decline) are recognized similar to how covariances are recognized in the mmrm package.
This would be nice for a future release. Currently, each model has its own individual function, even though the models are not very different. And we only provide a cell means parameterization for the treatment effect.
@kaskr mentioned https://github.com/bbolker/reformulas, a new package for processing model formulas.
- Dominant language
- R
- Stars
- 6
- Forks
- 2
- PR merge metrics
- No merged PRs in 30d
Getting set up
This project ships no dev container, Dockerfile or contributing guide, so setting up is up to you: start from its README, and see our first-contribution guide for the general steps.
First steps
- Read the whole issue, then the project's contributing guide.
- Comment on the issue to say you are picking it up — it saves two people doing the same work.
- Fork the repository and make your change on a branch.
- Open a pull request that references the issue number.
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