Many computer programs analyze the 2k factorial design.Table 13.14 is the output from Minitab. Although at firstglance the two tables seem somewhat different, they actuallyprovide the same information. The analysis of variance displayedin the lower portion of Table 13.14 presents F-ratioscomputed on important groups of model terms; main effects,two-way interactions, and the three-way interaction. The meansquare for each group of model terms was obtained by combiningthe sums of squares for each model component and dividingby the number of degrees of freedom associated with thatgroup of model terms.A t-test is used to test the significance of each individualterm in the model. These t-tests are shown in the upper portionof Table 13.14. Note that a “coefficient estimate” is given foreach variable in the full factorial model. These are actually theestimates of the coefficients in the regression model that wouldbe used to predict surface finish in terms of the variables in thefull factorial model. Each t-value is computed according to
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