Statistical modeling

General issues

For novel methods that are not described in detail in a separate paper, provide explicit description of method either in the text or as an appendix

Intrasubject fMRI Modeling Info

Statistical model and estimation method
- Multiple regression is the most common statistical model.
- Estimation methods are typically Ordinary Least Squares (OLS), OLS with adjustment for autocorrelation (i.e. variance correction and use of feffective degrees-of-freedom), or Generalized Least Squares (i.e. OLS after whitening)
Block/epoch-based or event-related model
Hemodynamic response function (HRF)
- Assumed HRF model (e.g. SPM's canonical difference of gammas HRF; FSL's Canonical Gmma HRF), HRF basis (list basis set) or estimated HRF (supply methods for estimating HRF)?
Additional regressors used (e.g. temporal derivatives, motion, behavioral covariates)
Any orthogonalization of regressors
Drift modeling/high-pass filtering
Autocorrelation model
- Model type (e.g. AR(1), AR(1)+WN or arbitrary autocorrelation and whether global or local (e.g. for SPM2/SPM5, 'Approximate AR(1) autocorrelation model estimated at omnibus F-significant voxels (P<0.001), used globally over the whole brain'; for FSL 'Autocorrelation function estimated locally at each voxel, tapered and regularized in space.').
Contrast construction.
- Exactly what terms are subtracted from what? Define these in terms of task or stimulus conditions (e.g., using abstract names such as AUDSTIM, VISSTIM) instead of underlying psychological concepts.

Group Modeling Info

Statistical model and estimation method, inference type (Mixed/Random Effects or Fixed)
E.g. "Mized effects inference with one sample t-test on summary statistic" (SPM2/SPM5).
E.g. "Mized effects inference with Bayesian 2-level model with fast approximation to posterior probability of activation." (FSL)
If fexed effects inference used, justify.
If more than 2-levels, describe the levels and assumptions of the model (e.g. are variances assumed equal between groups)
Repeated Measures?
If multiple measurements per subject, list method to account for within subject correlation, exact assumptions made about correlation/variance.
- E.g. "Within-subject correlation estimated at F-significant voxels (P<0.001), then used globally over the whole brain"; or, if variances for each measure are allowed to vary, "Within subject correlation and relative variance estimated..." (SPM)