by-lmby function

List of lm objects with a common model

The data is split into strata according to the levels of the grouping factors and individual lm fits are obtained for each stratum.

lm_by(data., formula., id = NULL, ...)

lmBy(formula., data., id = NULL, ...)

Arguments

• data.: A dataframe
• formula.: A linear model formula object of the form y ~ x1 + ... + xn | g1 + ... + gm. In the formula object, y represents the response, x1, ..., xn the covariates, and the grouping factors specifying the partitioning of the data according to which different lm fits should be performed.
• id: A formula describing variables from data which are to be available also in the output.
• ...: Additional arguments passed on to lm().

Returns

A list of lm fits.

Examples

bb <- lmBy(1 / uptake ~ log(conc) | Treatment, data=CO2)
coef(bb)

fitted(bb)
residuals(bb)

summary(bb)
coef(summary(bb))
coef(summary(bb), simplify=TRUE)

Author(s)

Søren Højsgaard, sorenh@math.aau.dk