# Validation

We run a simulation study to verify the models in `pmrm` are implemented correctly. For each simulation scenario (model type and disease progression trajectory), we:

1. Simulate 1000 datasets from the model using independent non-`RTMB` R code.
2. Fit the model to each simulated dataset using the `RTMB`-powered implementation.

Around half of the 50% confidence intervals from (2) should cover the true data-generating parameter values in (1). Likewise, around 95% of the 95% confidence intervals from (2) should cover the truth. In addition, we expect all models to converge.

# Implementation

    library(dplyr)
    library(ggplot2)
    library(knitr)
    library(readr)
    library(scales)

This simulation study is a `targets` pipeline in the `vignettes/validation/` directory of the source code of `pmrm`. To run the pipeline, change to that working directory and call `targets::tar_make()`. Due to the computational cost, we only run this pipeline once per release.

# Last run

We last ran the simulation pipeline with `pmrm` version 0.0.4 with GitHub commit hash .

# Convergence

The following table shows the percentage of fitted models that converged for each scenario.

    read_csv(file.path("validation", "convergence.csv")) |>
      mutate(convergence = label_percent()(convergence)) |>
      kable()

scenario | convergence
--- | ---
exponential_decline_nonproportional | 100%
exponential_decline_proportional | 100%
exponential_slowing_nonproportional | 100%
exponential_slowing_proportional | 100%
linear_decline_nonproportional | 100%
linear_decline_proportional | 100%
linear_slowing_nonproportional | 100%
linear_slowing_proportional | 100%

# Parameter coverage

The following plot shows the percentage of confidence intervals that covered the true parameter values. Coverage is shown separately for each parameter in each scenario. For reference, the expected coverage rate is shown as a horizontal solid in each facet.

    include_graphics(file.path("validation", "coverage.png"))