Unbalanced dataset
This is a simulated unbalanced dataset with three factors
and two numeric variables. There are true relationships among these variables.
This dataset can be useful in testing or illustrating messy-data situations.
There are no missing data, and there is at least one observation for every
factor combination; however, the "cells" attribute makes it simple
to construct subsets that have empty cells.
ubds
A data frame with 100 observations, 5 variables,
and a special "cells" attribute:
Factor with levels 1, 2, and 3
Factor with levels 1, 2, and 3
Factor with levels 1, 2, and 3
A numeric variable
A numeric variable
In addition, attr(ubds, "cells") consists of a named list of length 27 with the row numbers for
each combination of A, B, C. For example,
attr(ubds, "cells")[["213"]] has the row numbers corresponding
to levels A == 2, B == 1, C == 3. The entries are ordered by
length, so the first entry is the cell with the lowest frequency.
# Omit the three lowest-frequency cells low3 <- unlist(attr(ubds, "cells")[1:3]) messy.lm <- lm(y ~ (x + A + B + C)^3, data = ubds, subset = -low3)
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