5.23 Byrne and Taguchi (1987) discuss an experiment to see the effect of interference (x\), connector wall thickness (x2), insertion depth (x3), and amount of adhesive (x4) on the pull-off force for an elastometric connector to a nylon tube in an automotive application. The data follow. *1 -1 -1 -1 0 0 0 1 1 1 x2 -1 0 1 -1 0 1 -1 0 1 x3 -1 0 1 0 1 -1 1 -1 0 x4 -1 0 1 1 -1 0 0 1 -1 15.6 15.0 16.3 18.3 19.7 16.2 16.4 14.2 16.1 9.5 16.2 16.7 17.4 18.6 16.3 19.1 15.6 19.9 16.9 19.4 19.1 18.9 19.4 20.0 18.4 15.1 19.3 y 19.9 19.2 15.6 18.6 25.1 19.8 23.6 16.8 17.3 19.6 19.7 22.6 21.0 25.6 14.7 16.8 17.8 23.1 19.6 19.8 18.2 18.9 21.4 19.6 18.6 19.6 22.7 20.0 24.2 23.3 23.2 27.5 22.5 24.3 23.2 22.6 19.1 21.9 20.4 24.7 25.3 24.7 21.6 24.2 28.6

(a) Use GLMs to fit an appropriate model for the variance.

(b) Use this model as a basis for a weighted least squares estimation of the model for the distance.

(c) Discuss your results.