contrast treatment contrast Alejandra Gonzalez-Beltran Philippe Rocca-Serra Orlaith Burke adapted from multiple sources: http://pic.dhe.ibm.com/infocenter/spssstat/v20r0m0/index.jsp?topic=%2Fcom.ibm.spss.statistics.help%2Fidh_idd_genlin_emmeans.htm http://www.clayford.net/statistics/tag/helmert-contrasts/ http://www.aliquote.org/articles/tech/contrasts.html contr.treatment(n, base = 1, contrasts = TRUE, sparse = FALSE) http://stat.ethz.ch/R-manual/R-patched/library/stats/html/contrast.html treatment contrast is a contrast which allows to test how linear model coefficients of categorical variables are interpreted in case where the “first” level (aka, the baseline) is included into the intercept and all subsequent levels have a coefficient that represents their difference from the baseline. requires discussion