title: Multiple Subject Barycentric Discriminant Analysis (MUSUBADA): how to assign scans to categories without using spatial normalization.
abstract: We present a new discriminant analysis (DA) method called Multiple Subject Barycentric Discriminant Analysis (MUSUBADA) suited for analyzing fMRI data because it handles datasets with multiple participants that each provides different number of variables (i.e., voxels) that are themselves grouped into regions of interest (ROIs). Like DA, MUSUBADA (1) assigns observations to predefined categories, (2) gives factorial maps displaying observations and categories, and (3) optimally assigns observations to categories. MUSUBADA handles cases with more variables than observations and can project portions of the data table (e.g., subtables, which can represent participants or ROIs) on the factorial maps. Therefore MUSUBADA can analyze datasets with different voxel numbers per participant and, so does not require spatial normalization. MUSUBADA statistical inferences are implemented with cross-validation techniques (e.g., jackknife and bootstrap), its performance is evaluated with confusion matrices (for fixed and random models) and represented with prediction, tolerance, and confidence intervals. We present an example where we predict the image categories (houses, shoes, chairs, and human, monkey, dog, faces,) of images watched by participants whose brains were scanned. This example corresponds to a DA question in which the data table is made of subtables (one per subject) and with more variables than observations.
authors.affiliation: School of Behavioral and Brain Sciences, University of Texas at Dallas, MS: GR4.1, 800 West Campbell Road, Richardson, TX 75080-3021, USA. herve@utdallas.edu
authors.forename: Hervé
authors.initials: H
authors.lastname: Abdi
authors.forename: Lynne J
authors.initials: LJ
authors.lastname: Williams
authors.forename: Andrew C
authors.initials: AC
authors.lastname: Connolly
authors.forename: M Ida
authors.initials: MI
authors.lastname: Gobbini
authors.forename: Joseph P
authors.initials: JP
authors.lastname: Dunlop
authors.forename: James V
authors.initials: JV
authors.lastname: Haxby
mesh_terms: D000818:Animals; D001921:Brain / Q000502:physiology*; D003627:Data Interpretation, Statistical; D016002:Discriminant Analysis; D004285:Dogs; D005145:Face; D005260:Female; D000882:Haplorhini; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000523:psychology*; D008297:Male