one_source_priors_params: Adjust Bayesian priors - One Source Trophic Position

Description

Adjust priors for one source trophic position model derived from Post 2002.

Usage

one_source_priors_params(
  n1 = NULL,
  n1_sigma = NULL,
  dn = NULL,
  dn_sigma = NULL,
  tp_lb = NULL,
  tp_ub = NULL,
  sigma_lb = NULL,
  sigma_ub = NULL,
  bp = FALSE
)

Value

stanvars object to be used with brms() call.

Arguments

n1: mean ($\mu$) prior for the mean $\delta^{15}$N baseline. Defaults to 9.
n1_sigma: variance ($\sigma$) for the mean $\delta^{15}$N baseline. Defaults to 1.
dn: mean ($\mu$) prior value for $\Delta$N. Defaults to 3.4.
dn_sigma: variance ($\sigma$) for $\delta^{15}$N. Defaults to 0.25.
tp_lb: lower bound prior for trophic position. Defaults to 2.
tp_ub: upper bound prior for trophic position. Defaults to 10.
sigma_lb: lower bound prior for $\sigma$. Defaults to 0.
sigma_ub: upper bound prior for $\sigma$. Defaults to 10.
bp: logical value that controls whether informed priors are supplied to the model for $\delta^{15}$N baseline. Default is FALSE meaning the model will use uninformed priors, however, the supplied data.frame needs values for $\delta^{15}$N baseline (n1).

Details

$$\delta^{15}N = \delta^{15} N_1 + \delta N \times (tp - \lambda_1)$$

This function allows the user to adjust the priors for the following variables in the equation above:

The mean (n1; $\mu$) and variance (n1_sigma; $\sigma$) for the mean $\delta^{15}$N for a given baseline ($\delta^{15}N_1$). This prior assumes a normal distribution.
The mean (dn; $\mu$) and variance (dn_sigma; $\sigma$) of $\Delta$N (i.e, trophic enrichment factor). This prior assumes a normal distribution.
The lower (tp_lb) and upper (tp_ub) bounds for trophic position. This prior assumes a uniform distribution.
The lower (sigma_lb) and upper (sigma_ub) bounds for variance ($\sigma$). This prior assumes a uniform distribution.

Examples

Run this code

one_source_priors_params()