18. Nail varnish experiment, continued The nail varnish experiment, introduced in Example 6.5.1, page 159, concerned the dissolving time of three brands of nail varnish in two brands of solvent. There were r = 5 observations on each treatment combination, and the two-way main-effects model (6.2.3) was used. The least squares estimate of the contrast comparing brand 3 with the average of the other two brands was $ (\hat{\beta}_1 + \hat{\beta}_2) - \hat{\beta}_3$ = -0.341, with associated variance 30²/20. From Example 6.5.2, msE = 8.3375.