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brms.mmrm (development)

Guardrails to ensure the appropriateness of marginal mean estimation

  • Require a new formula argument in brm_marginal_draws().
  • Change class name "brm_data" to "brms_mmrm_data" to align with other class names.
  • Create a special "brms_mmrm_formula" class to wrap around the model formula. The class ensures that formulas passed to the model were created by brms_formula(), and the attributes store the user’s choice of fixed effects.
  • Create a special "brms_mmrm_model" class for fitted model objects. The class ensures that fitted models were created by brms_model(), and the attributes store the "brms_mmrm_formula" object in a way that brms itself cannot modify.
  • Deprecate use_subgroup in brm_marginal_draws(). The subgroup is now always part of the reference grid when declared in brm_data(). To marginalize over subgroup, declare it in covariates instead.
  • Prevent overplotting multiple subgroups in brm_plot_compare().
  • Update the subgroup vignette to reflect all the changes above.

Custom estimation of marginal means

  • Implement a new brm_transform_marginal() to transform model parameters to marginal means (#53).
  • Use brm_transform_marginal() instead of emmeans in brm_marginal_draws() to derive posterior draws of marginal means based on posterior draws of model parameters (#53).
  • Explain the custom marginal mean calculation in a new inference.Rmd vignette.
  • Rename methods.Rmd to model.Rmd since inference.Rmd also discusses methods.

brms.mmrm 0.1.0

CRAN release: 2024-02-15

  • Deprecate brm_simulate() in favor of brm_simulate_simple() (#3). The latter has a more specific name to disambiguate it from other simulation functions, and its parameterization conforms to the one in the methods vignette.
  • Add new functions for nuanced simulations: brm_simulate_outline(), brm_simulate_continuous(), brm_simulate_categorical() (#3).
  • In brm_model(), remove rows with missing responses. These rows are automatically removed by brms anyway, and by handling by handling this in brms.mmrm, we avoid a warning.
  • Add subgroup analysis functionality and validate the subgroup model with simulation-based calibration (#18).
  • Zero-pad numeric indexes in simulated data so the levels sort as expected.
  • In brm_data(), deprecate level_control in favor of reference_group.
  • In brm_data(), deprecate level_baseline in favor of reference_time.
  • In brm_formula(), deprecate arguments effect_baseline, effect_group, effect_time, interaction_baseline, and interaction_group in favor of baseline, group, time, baseline_time, and group_time, respectively.
  • Propagate values in the missing column in brm_data_change() such that a value in the change from baseline is labeled missing if either the baseline response is missing or the post-baseline response is missing.
  • Change the names in the output of brm_marginal_draws() to be more internally consistent and fit better with the addition of subgroup-specific marginals (#18).
  • Allow brm_plot_compare() and brm_plot_draws() to select the x axis variable and faceting variables.
  • Allow brm_plot_compare() to choose the primary comparison of interest (source of the data, discrete time, treatment group, or subgroup level).

brms.mmrm 0.0.2

CRAN release: 2023-08-18

  • Fix grammatical issues in the description.

brms.mmrm 0.0.1

  • First version.