Attach length-diffusion uncertainty to fixed expected growth increments

This helper is used when a mean growth curve has been estimated outside the stock assessment and supplied as deterministic tag and population increments. Only the length-diffusion and observation-error components are evaluated inside the assessment.

Usage

get_growth_increment_fixed(
  midpoint,
  mean_increment,
  gsigma,
  gobs = NULL,
  gmin = 1e-04,
  tau = 1,
  length_power = -1,
  variance_reference_length = 60
)

Arguments

midpoint

Release lengths or assessment-bin midpoints (mm).

mean_increment

Fixed expected increments corresponding to midpoint and tau (mm).

gsigma

Process diffusion SD at variance_reference_length in mm per square-root year.

gobs

Observation-error SD (mm); use NULL or zero to omit it.

gmin

Minimum process SD scale.

tau

Elapsed time in years.

length_power

Power governing the length dependence of process SD.

variance_reference_length

Reference length for gsigma (mm).

Value

A list with fixed expected increment gi and total SD sigma.