2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/130833We study the geometric structure of the statistical models for two-by-two contingency tables. One or two odds ratios are fixed and the corresponding models are shown to be a portion of a ruled quadratic surface or a segment. Some pointers to the general case of two-way contingency tables are also given and an application to case-control studies is presented.References were not displaying properly in the previous versionStatistics TheoryAlgebraic Geometry14Q99;62H17text