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This is the first release of epidist on CRAN.
epidist estimates epidemiological delay distributions, such
as the incubation period or the delay from onset to report, using
brms. It corrects for the common biases in these data:
interval censoring of the primary and secondary events, right
truncation, left truncation, and the dynamical bias from a growing or
shrinking epidemic. It provides a naive model, a latent model that
samples the unobserved event times, and a marginal model that integrates
them out through primarycensored. It also provides an
experimental meta model, which fits published summary estimates jointly
with individual level data and adjusts each summary for how its study
was estimated. Delays can follow a lognormal, gamma, Weibull or
generalised gamma distribution. Every distributional parameter can take
a brms formula, so delays can vary with covariates, over
time or between groups with partial pooling. Tools for preparing data,
setting priors, simulating data, summarising and plotting fitted delay
distributions, and passing them on to other packages complete the
workflow. The meta model is still experimental and its interface may
change.
gengamma(), a generalised gamma delay family in
the Prentice parameterisation of flexsurv::dgengamma(), for
the naive, latent, marginal and meta models. The Weibull and gamma are
special cases and the lognormal is its limit. Closes #644.epidist_meta_leave_one_out() gains a
studies argument that holds out only the studies named, so
a model with many studies can be checked against its largest few.epidist now needs
primarycensored 1.6.0 or later. Closes #807.epidist_gen_meta_log_lik() and
as_epidist_meta_model() now states the cost of
log_lik() and loo() for meta model summary
rows, and how ndraws reduces it. Closes #705.simulate_*() functions and to
epidist_family(), epidist_formula(),
epidist_prior() and epidist_stancode().brms
functions, so log_lik(), posterior_predict()
and posterior_epred() use epidist’s own
functions for every family. These cover the lognormal, gamma, Weibull,
exponential and generalised gamma families. For any other family these
functions now give an error.epidist_meta_leave_one_out() runs the chains of each
refit in parallel by default, where they previously ran one after
another. Its new cores argument defaults to the
mc.cores option where it is set and otherwise to one core
per chain.print() of an epidist_multivariate object
writes its header as output rather than a message, so
suppressMessages() no longer hides it.bookdown::html_vignette2,
which cuts the installed size of the package by about 4Mb.sierra_leone_ebola_data source by its DOI and
corrected its column descriptions.BH, Rcpp,
RcppEigen, pkgdown and usethis
suggested dependencies.epireview is no longer a suggested dependency, so the
package needs no repository beyond CRAN.
epidist_estimates_epireview() takes any table with the
columns epireview uses.This release adds a meta model for fitting to published summary estimates, exponentially growing primary events, left truncation, and a new set of tools for post-processing and plotting fitted models. It also removes several functions and changes some interfaces, as listed below.
predict_delay_parameters() and
predict_dpar() are removed in favour of
delay_parameter_draws(), and add_mean_sd() in
favour of add_summaries(). See #471.epidist_family_param() and
epidist_transform_data() are now internal. Extensions
implement epidist_family_model() and
epidist_transform_data_model() instead. See #79.is_epidist_*() predicates share one signature,
is_epidist_<class>(data), and no longer take
.... Closes #706.epidist data objects share an epidist_data
class, checked by is_epidist_data(). They re-check
themselves when modified and drop any class whose requirements they no
longer meet, with a warning. See ?epidist_data and
#399.cmdstanr is no longer a suggested dependency. Tests and
examples fit through rstan, and cmdstanr
remains available as a brms backend. See #687 and
#688.brms 2.23.0 and
primarycensored 1.5.2. The Remotes field is
removed, so all dependencies resolve from CRAN. See #592 and #727.as_epidist_meta_model(), which
fits published summary estimates jointly with individual level data.
Each summary is forward modelled from the study’s own estimation
procedure, so estimates that did not adjust for censoring or truncation
still contribute unbiased information. It is experimental and its
interface may change. See #620.as_epidist_estimates_data(),
epidist_estimates_summaries(),
epidist_estimates_parameters(),
epidist_estimates_epireview() and
as_epidist_multivariate() for preparing published
estimates. They cover means, standard deviations, quantiles, standard
errors, fitted distribution parameters and summaries with a covariance,
and check the inputs for common problems. See #620.epidist_gen_meta_log_lik() and
epidist_gen_meta_predict(), so log_lik(),
loo() and posterior predictions work for meta model fits.
See #620.epidist_meta_leave_one_out(), which refits a meta
model once per study with that study held out and reports how the delay
mean and standard deviation change. Closes #642.simulate_study(), which applies a published
study’s observation and estimation procedure to a simulated line list.
Closes #672.NA or uncertain growth_rate values, sharing it
with individual level data. Closes #678.primary = "expgrowth" for the latent, marginal and meta
models. The growth rate is a distributional parameter, so it takes a
formula and prior. See #489 and #618.delay_min argument to
as_epidist_marginal_model(), also supported by the meta
model. See #588 and #596.delay_parameter_draws(),
add_delay_parameter_draws(), add_summaries(),
epidist_strata() and delay_summary_draws() for
posterior draws of the delay distribution and its mean, standard
deviation and quantiles. epidist_newdata() builds the
newdata they need. See #280, #471 and #667.plot_events(), plot_delays(), and
plot() and ggplot2::autoplot() methods for
delay draws. plot_delays() also gives a posterior
predictive check of a fitted model. See #670, #689 and #743.distspec::as_dist_spec() method for fitted
models. See #712.simulate_dates(), which turns simulated event
times into censored dates.epidist_gen_log_lik(), and made its generic
method linear in the number of posterior draws. See #79, #476 and
#646.epidist_prior() no longer warns about user priors on
valid brms parameters, and lists unmatched priors clearly.
See #483.epidist() now restores the PKG_CPPFLAGS
and PKG_LIBS environment variables that rstan
leaves set. See #532.epidist_gen_log_lik() method now normalises
over delay_min when there is no right truncation. Closes
#646.delay_parameter_draws() no longer passes on the
brms warning about the infinite observation times
epidist uses. Closes #718.dplyr
verbs, so plot() still dispatches. Closes #721.brms functions. See
#420.epidist.
See #596 and #620.L (left truncation) parameter to the
primarycensored_lpmf call in the marginal model. See
#583.primarycensored (>= 1.4.0) version bound to
DESCRIPTION.primarycensored_lpmf and ODE/distribution helpers) with
pcd_load_stan_functions(dependencies = TRUE) instead of
loading all functions. See #582.check-cmdstan workflow to also check marginal
model Stan syntax.as_epidist_marginal_model(). See #565.Hotfix release to patch a change in how the grepl
function works in new versions of R.
This release adds support for a wider range of distributions in the marginal model, improves documentation with new vignettes and FAQ sections, enhances the getting started guide with clearer examples of model comparison, and fixes several bugs related to parameter bounds and likelihood calculations.
primarycensored in the marginal model. See #540.posterior package with epidist models,
particularly for working with random variables (rvars) to
propagate uncertainty in calculations. See #547.marginaleffects package with epidist models.
See #547.predict_delay_parameters() where it
couldn’t detect brms families when used directly. See #549.This release adds a new marginal model based on
primarycensored which provides a more efficient approach
for fitting delay distributions compared to the existing latent model.
We’ve also improved data handling by adding support for aggregated data
across all models, added comprehensive examples using real world data,
and enhanced documentation based on user feedback. The package has also
undergone significant internal improvements including generalised Stan
reparameterisation and improved data transformation methods.
As part of this release we have moved from @athowes maintaining the package (who led the initial package development, implementation of the S3 infrastructure, implementation of the core models, and wrote the first versions of the getting started vignette, Ebola case study, FAQ section, and the approximate inference vignette) to @seabbs maintaining the package.
primarycensored. This can be specified using
as_epidist_marginal_model(). This is currently limited to
Weibull, log-normal, and gamma distributions with uniform primary
censoring but this will be generalised in future releases. See
#426.weight argument to
as_epidist_marginal_model() to allow for weighted data (for
example count data) to be used in the marginal model. See #509.epidist_aggregate_data method to
as_epidist_marginal_model() to allow straightforward use of
the marginal model with aggregated data. See #510.epidist_aggregate_data method to
as_epidist_latent_model() to allow straightforward use of
the latent model with aggregated data. See #510.epidist_aggregate_data method to
as_epidist_naive_model() to allow straightforward use of
the naive model with aggregated data. See #510.epidist(). See #473.enforce_presence argument to
epidist_prior() to allow for priors to be specified if they
do not match existing parameters. See #474.merge argument to epidist_prior()
to allow for not merging user and package priors. See #474.brms and then extracting the reparameterisation. See
#474.transform_data S3 method to allow for data to
be transformed for specific models. This is specifically useful for the
marginal model at the moment as it allows reducing the data to its
unique strata. See #474.epidist_aggregate_data class to handle
pre-aggregated line list data. See #510.as_epidist_aggregate_data() method for
epidist_linelist_data objects to allow for easy conversion
to aggregate data. See #510.as_epidist_linelist_data() method for
epidist_aggregate_data objects to allow for easy conversion
to linelist data. See #510.sierra_leone_ebola_data to the
package. See #510.epidist_transform_data() methods work for the marginal and
naive models. See #510.epinowcast standards.
See #467.primarycensored that
doesn’t make use of size(). This fixes some Mac compilation
edge cases. See #524.This is the first minor release of epidist intended for
early test users of the package. As some features may change, the
package is marked as experimental. We expect to release a stable 1.0.0
version shortly.
The epidist package implements models for
epidemiological delay distributions. It uses brms to perform
Bayesian inference.
One data format is currently available:
Two statistical models are currently available:
brmsThe package is readily extensible to additional models via an S3 class based system. In particular, model fitting with [epidist()] is possible using S3 classes for custom:
We provide functionality for post-processing.
Alternatively, users may directly use tidybayes for
specific families.
Three vignettes are available. There is also a frequently asked questions section.
These binaries (installable software) and packages are in development.
They may not be fully stable and should be used with caution. We make no claims about them.
Health stats visible at Monitor.