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R-list, 1. Given a formula (f) w variables referencing some data set (dat), is there any easier/faster way than this to get the names (in character form) of the variables on the RHS of '~' ? dat <- data.frame(x1 = x1 <- rnorm(100,0,1), x2 = x2 <- rnorm(100,0,1), y = x1 + x2 + rnorm(100,0,1)) f <- y ~ x1 + x2 mf <- model.frame(f, data=dat) mt <- attr(mf,

This is a question regarding the 'regTermTest' function in the 'survey' package. Imagine Z as a three level factor variable, and code ZB and ZC as the two corresponding dummy variables. X is a continuous variable. In a 'glm' of Y on Z and X, say, how do the two test specifications test.terms = c("ZB:X","ZC:X") # and test.terms = ~ ZB:X + ZC:X in