stan_jsdm: Fit jsdm models in Stan

In fseaton/jsdmstan: Fitting jSDMs in Stan

Fit jsdm models in Stan

Description

This function fits joint Species Distribution models in Stan, using either a generalised linear latent variable model approach (method = "gllvm"), or a multivariate generalised linear mixed model approach (method = "mglmm").

Usage

stan_jsdm(X, ...)

## Default S3 method:
stan_jsdm(
  X = NULL,
  Y = NULL,
  species_intercept = TRUE,
  method,
  dat_list = NULL,
  family,
  site_intercept = "none",
  D = NULL,
  prior = jsdm_prior(),
  site_groups = NULL,
  beta_param = "unstruct",
  Ntrials = NULL,
  zi_param = "constant",
  zi_X = NULL,
  save_data = TRUE,
  iter = 4000,
  log_lik = TRUE,
  ...
)

## S3 method for class 'formula'
stan_jsdm(formula, data = list(), ...)

Arguments

X	The covariates matrix, with rows being site and columns being covariates. Ignored in favour of data when formula approach is used to specify model.
...	Arguments passed to rstan::sampling()
Y	Matrix of species by sites. Rows are assumed to be sites, columns are assumed to be species
species_intercept	Whether the model should be fit with an intercept by species, by default TRUE
method	Whether to fit a GLLVM or MGLMM model, details in description
dat_list	Alternatively, data can be given to the model as a list containing Y, X, N, S, K, and site_intercept. See output of jsdm_sim_data() for an example of how this can be formatted.
family	is the response family, must be one of "gaussian", "neg_binomial", "poisson", "binomial", "bernoulli", or "zi_poisson". Regular expression matching is supported.
site_intercept	Whether a site intercept should be included, potential values "none" (no site intercept), "grouped" (a site intercept with hierarchical grouping) or "ungrouped" (site intercept with no grouping)
D	The number of latent variables within a GLLVM model
prior	Set of prior specifications from call to jsdm_prior()
site_groups	If the site intercept is grouped, a vector of group identities per site
beta_param	The parameterisation of the environmental covariate effects, by default "unstruct". See details for further information.
Ntrials	For the binomial distribution the number of trials, given as either a single integer which is assumed to be constant across sites or as a site-length vector of integers.
zi_param	For the zero-inflated families, whether the zero-inflation parameter is a species-specific constant (default, "constant"), or varies by environmental covariates ("covariate").
zi_X	If zi = "covariate", the matrix of environmental predictors that the zero-inflation is modelled in response to. If there is not already an intercept column (identified by all values being equal to one), one will be added to the front of the matrix.
save_data	If the data used to fit the model should be saved in the model object, by default TRUE.
iter	A positive integer specifying the number of iterations for each chain, default 4000.
log_lik	Whether the log likelihood should be calculated in the generated quantities (by default TRUE), required for loo
formula	The formula of covariates that the species means are modelled from
data	Dataframe or list of covariates.

Details

Environmental covariate effects ("betas") can be parameterised in two ways. With the "cor" parameterisation all covariate effects are assumed to be constrained by a correlation matrix between the covariates. With the "unstruct" parameterisation all covariate effects are assumed to draw from a simple distribution with no correlation structure. Both parameterisations can be modified using the prior object. Families supported are the Gaussian family, the negative binomial family, the Poisson family, the binomial family (with number of trials specificied using the Ntrials parameter), the Bernoulli family (the special case of the binomial family where number of trials is equal to one), the zero-inflated Poisson and the zero-inflated negative binomial. For both zero-inflated families the zero-inflation is assumed to be a species-specific constant.

Value

A jsdmStanFit object, comprising a list including the StanFit object, the data used to fit the model plus a few other bits of information. See jsdmStanFit for details.

Methods (by class)

• stan_jsdm(default): this is the default way of doing things

• stan_jsdm(formula): Formula interface

Examples

## Not run: 
# MGLMM - specified by using the mglmm aliases and with direct reference to Y and
# X matrices:
mglmm_data <- mglmm_sim_data(
  N = 100, S = 10, K = 3,
  family = "gaussian"
)
mglmm_fit <- stan_mglmm(
  Y = mglmm_data$Y, X = mglmm_data$X,
  family = "gaussian"
)
mglmm_fit

# You can also run a model by supplying the data as a list:
gllvm_data <- jsdm_sim_data(
  method = "gllvm", N = 100, S = 6, D = 2,
  family = "bernoulli"
)
gllvm_fit <- stan_jsdm(
  dat_list = gllvm_data, method = "gllvm",
  family = "bernoulli"
)
gllvm_fit

## End(Not run)

fseaton/jsdmstan documentation built on Sept. 29, 2024, 6:40 p.m.