An experiment was conducted to investigate leaking current in a SOS MOSFETS device. The purpose of the experiment was to investigate how leakage current varies as the channel length changes. Four channel lengths were selected. For each channel length, five different widths were also used, and width is to be considered a nuisance factor. The data are as follows:

(a) Test the hypothesis that mean leakage voltage does not depend on the channel length, using a = 0.05.
(b) Analyze the residuals from this experiment. Comment on the residual plots.

Width Channel Length 3 0.7 0.9 0.8 0.8 1.0 0.8 0.8 0.9 0.9 1.0 3 0.9 1.0 1.7 2.0 4.0 1.0 1.5 2.0 3.0 20.0