title: Ragu: a free tool for the analysis of EEG and MEG event-related scalp field data using global randomization statistics.
abstract: We present a program (Ragu; Randomization Graphical User interface) for statistical analyses of multichannel event-related EEG and MEG experiments. Based on measures of scalp field differences including all sensors, and using powerful, assumption-free randomization statistics, the program yields robust, physiologically meaningful conclusions based on the entire, untransformed, and unbiased set of measurements. Ragu accommodates up to two within-subject factors and one between-subject factor with multiple levels each. Significance is computed as function of time and can be controlled for type II errors with overall analyses. Results are displayed in an intuitive visual interface that allows further exploration of the findings. A sample analysis of an ERP experiment illustrates the different possibilities offered by Ragu. The aim of Ragu is to maximize statistical power while minimizing the need for a-priori choices of models and parameters (like inverse models or sensors of interest) that interact with and bias statistics.
authors.affiliation: Department of Psychiatric Neurophysiology, University Hospital of Psychiatry Bern, University of Bern, 3000 Bern 60, Bolligenstr. 111, Switzerland. thomas.koenig@puk.unibe.ch
authors.forename: Thomas
authors.initials: T
authors.lastname: Koenig
authors.forename: Mara
authors.initials: M
authors.lastname: Kottlow
authors.forename: Maria
authors.initials: M
authors.lastname: Stein
authors.forename: Lester
authors.initials: L
authors.lastname: Melie-García
mesh_terms: D000328:Adult; D001921:Brain / Q000502:physiology*; D004569:Electroencephalography / Q000379:methods* / Q000706:statistics & numerical data; D005071:Evoked Potentials / Q000502:physiology*; D006801:Humans; D015225:Magnetoencephalography / Q000379:methods* / Q000706:statistics & numerical data; D011897:Random Allocation; D012535:Scalp / Q000502:physiology*; D012815:Signal Processing, Computer-Assisted; D012984:Software / Q000706:statistics & numerical data; D055815:Young Adult