estimate_betas.fmri_dataset: Estimate betas using various regression methods

In bbuchsbaum/fmrireg: R package for the anlysis of fmri data

Estimate betas using various regression methods

Description

This function estimates betas (regression coefficients) for fixed and random effects using various regression methods including mixed models, least squares, and PLS.

Usage

## S3 method for class 'fmri_dataset'
estimate_betas(
  x,
  fixed = NULL,
  ran,
  block,
  method = c("mixed", "mixed_cpp", "lss", "lss_naive", "lss_cpp", "pls", "pls_global",
    "ols"),
  basemod = NULL,
  maxit = 1000,
  fracs = 0.5,
  progress = TRUE,
  ...
)

Arguments

x	An object of class fmri_dataset representing the fMRI dataset.
fixed	A formula specifying the fixed regressors that model constant effects (i.e., non-varying over trials).
ran	A formula specifying the random (trialwise) regressors that model single trial effects.
block	A formula specifying the block factor.
method	The regression method for estimating trialwise betas; one of "mixed", "mixed_cpp", "lss", "lss_naive", "lss_cpp", "pls", "pls_global", or "ols".
basemod	A baseline_model instance to regress out of data before beta estimation (default: NULL).
maxit	Maximum number of iterations for optimization methods (default: 1000).
fracs	Fraction of voxels used for prewhitening.
progress	Logical; show progress bar.
...	Additional arguments passed to the estimation method.

Value

A list of class "fmri_betas" containing the following components:

• betas_fixed: NeuroVec object representing the fixed effect betas.

• betas_ran: NeuroVec object representing the random effect betas.

• design_ran: Design matrix for random effects.

• design_fixed: Design matrix for fixed effects.

• design_base: Design matrix for baseline model.

• basemod: Baseline model object.

• fixed_model: Fixed effect model object.

• ran_model: Random effect model object.

• estimated_hrf: The estimated HRF vector (NULL for most methods).

See Also

fmri_dataset, baseline_model, event_model

Examples

## Not run: 
facedes <- read.table(system.file("extdata", "face_design.txt", package = "fmrireg"), header=TRUE)
facedes$frun <- factor(facedes$run)
scans <- paste0("rscan0", 1:6, ".nii")

dset <- fmri_dataset(scans=scans, mask="mask.nii", TR=1.5, 
        run_length=rep(436,6), event_table=facedes)
fixed = onset ~ hrf(run)
ran = onset ~ trialwise()
block = ~ run

betas <- estimate_betas(dset, fixed=fixed, ran=ran, block=block, method="mixed")

## End(Not run)

bbuchsbaum/fmrireg documentation built on June 10, 2025, 8:18 p.m.