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.

Usage

ubds

Format

A data frame with 100 observations, 5 variables, and a special "cells" attribute:

A

Factor with levels 1, 2, and 3

B

Factor with levels 1, 2, and 3

C

Factor with levels 1, 2, and 3

x

A numeric variable

y

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.

Examples

 # 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)