title: Take two orthogonals and call me in the morning.
abstract: Analysis of variance (ANOVA) is used to prevent inflated type I error when hypothesis testing involves comparing more than two groups. If an ANOVA result indicates a statistically significant difference exists somewhere within, the next task is to discover exactly which combination or combinations of those groups account for the significant difference. Among many methods available for that exploration, orthogonal contrasts and relatively simple graphs are noteworthy.
authors.affiliation: Applied Epidemiology, Sidney, British Columbia, Canada.
authors.forename: David
authors.initials: D
authors.lastname: Birnbaum
mesh_terms: D000704:Analysis of Variance; D003627:Data Interpretation, Statistical; D013502:General Surgery; D006302:Health Services Research / Q000706:statistics & numerical data*; D006801:Humans; D007902:Length of Stay; D011182:Postoperative Care; D012984:Software