anscombe <- data.frame(
 x1 = c(10, 8, 13, 9, 11, 14, 6, 4, 12, 7, 5),
 x2 = c(10, 8, 13, 9, 11, 14, 6, 4, 12, 7, 5),
 x3 = c(10, 8, 13, 9, 11, 14, 6, 4, 12, 7, 5),
 x4 = c(8, 8, 8, 8, 8, 8, 8, 19, 8, 8, 8),
 y1 = c(8.04, 6.95,  7.58, 8.81, 8.33, 9.96, 7.24, 4.26,10.84, 4.82, 5.68),
 y2 = c(9.14, 8.14,  8.74, 8.77, 9.26, 8.1,  6.13, 3.1,  9.13, 7.26, 4.74),
 y3 = c(7.46, 6.77, 12.74, 7.11, 7.81, 8.84, 6.08, 5.39, 8.15, 6.42, 5.73),
 y4 = c(6.58, 5.76,  7.71, 8.84, 8.47, 7.04, 5.25, 12.5, 5.56, 7.91, 6.89)
)