two_source_priors_params {trps}R Documentation

Adjust Bayesian priors - Two Source Trophic Position

Description

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

Usage

two_source_priors_params(
  a = NULL,
  b = NULL,
  c1 = NULL,
  c1_sigma = NULL,
  c2 = NULL,
  c2_sigma = NULL,
  n1 = NULL,
  n1_sigma = NULL,
  n2 = NULL,
  n2_sigma = NULL,
  dn = NULL,
  dn_sigma = NULL,
  tp_lb = NULL,
  tp_ub = NULL,
  sigma_lb = NULL,
  sigma_ub = NULL,
  bp = FALSE
)

Arguments

a

(\alpha) exponent of the random variable for beta distribution. Defaults to 1. See beta distribution for more information.

b

(\beta) shape parameter for beta distribution. Defaults to 1. See beta distribution for more information.

c1

mean (\mu) prior for the mean of the first \delta^{13}C baseline. Defaults to -21.

c1_sigma

variance (\sigma)for the mean of the first \delta^{13}C baseline. Defaults to 1.

c2

mean (\mu) prior for or the mean of the second \delta^{13}C baseline. Defaults to -26.

c2_sigma

variance (\sigma)for the mean of the first \delta^{13}C baseline. Defaults to 1.

n1

mean (\mu) prior for the mean of the first \delta^{15}N baseline. Defaults to 8.

n1_sigma

variance (\sigma)for the mean of the first \delta^{15}N baseline. Defaults to 1.

n2

mean (\mu) prior for or the mean of the second \delta^{15}N baseline. Defaults to 9.5.

n2_sigma

variance (\sigma) for the mean of the second \delta^{15}N baseline. Defaults to 1.

dn

mean (\mu) prior value for \DeltaN. Defaults to 3.4.

dn_sigma

variance (\sigma) for \delta^{15}N. Defaults to 0.25.

tp_lb

lower bound for priors for trophic position. Defaults to 2.

tp_ub

upper bound for priors for trophic position. Defaults to 10.

sigma_lb

lower bound for priors for \sigma. Defaults to 0.

sigma_ub

upper bound for priors for \sigma. Defaults to 10.

bp

logical value that controls whether informed priors are supplied to the model for both \delta^{15}N and \delta^{15}C baselines. Default is FALSE meaning the model will use uninformed priors, however, the supplied data.frame needs values for both \delta^{15}N and \delta^{15}C baseline (c1, c2, n1, and n2).

Details

We will use the following equations from Post 2002:

  1. \delta^{13}C_c = \alpha * (\delta ^{13}C_1 - \delta ^{13}C_2) + \delta ^{13}C_2

  2. \delta^{15}N = \Delta N \times (tp - \lambda_1) + n_1 \times \alpha + n_2 \times (1 - \alpha)

  3. \delta^{15}N = \Delta N \times (tp - (\lambda_1 \times \alpha + \lambda_2 \times (1 - \alpha))) + n_1 \times \alpha + n_2 \times (1 - \alpha)

Value

stanvars object to be used with brms() call.

See Also

two_source_priors(), two_source_model(), and brms::brms()

Examples

two_source_priors_params()

[Package trps version 0.1.0 Index]