get_lower_upper: Get Default Parameter Ranges for a Model

In dRiftDM: Estimating (Time-Dependent) Drift Diffusion Models

Get Default Parameter Ranges for a Model

Description

get_lower_upper() returns suggested default values for parameter bounds of a drift_dm model. The function inspects the model's component functions (e.g., drift, boundary, non-decision time, start) and provides heuristic defaults for some of the pre-built components. Only parameters that are currently considered free in the model are returned.

Usage

get_lower_upper(object, ...)

## S3 method for class 'drift_dm'
get_lower_upper(object, ..., warn = TRUE)

Arguments

object	a drift_dm model.
...	additional arguments passed forward to the respective method.
warn	a single logical, if TRUE issue a warning listing components and parameters where no defaults could be provided.

Details

Supported components include: mu_constant, mu_dmc, mu_ssp, b_constant, x_uniform, x_beta, nt_constant, nt_uniform, nt_truncated_normal. For some defaults we use the model's discretization (dt, dx) to ensure sensible minima.

If a component is not recognized (or refers to currently unsupported components), no defaults are provided for that component. When warn = TRUE, a single warning lists components without defaults and any free parameters that remain unmatched. In this case, the user has to add the missing parameter ranges before attempting to fit the model.

The default ranges are heuristics intended to provide a reasonable starting point for new users. They are not guaranteed to be appropriate for every model or data set. Always review and, if needed, adjust the returned values as needed.

Value

a list with two named numeric vectors:

• lower — suggested lower bounds for free parameters

• upper — suggested upper bounds for free parameters

Examples

# get a model for the example
model <- dmc_dm(obs_data = dmc_synth_data)

# get the parameter ranges
lu <- get_lower_upper(model)
lu$lower
lu$upper

# then continue to estimate
# estimate_dm(model, lower = lu$lower, upper = lu$upper, optimizer = "nmkb")

dRiftDM documentation built on Dec. 1, 2025, 5:08 p.m.