Check the assumptions for the factorial design ANOVA of Exercise 14.36.

Data from Exercise 14.36

A trade-off study regarding the inspection and test of transformer parts was conducted by the quality department of a major defense contractor. The investigation was structured to examine the effects of varying inspection levels and incoming test times to detect early part failure or fatigue. The levels of inspection selected were full military inspection (A), reduced military specification level (B), and commercial grade (C). Operational burn-in test times chosen for this study were at 1-hour increments from 1 hour to 9 hours. The response was failures per thousand pieces obtained from samples taken from lot sizes inspected to a specified level and burned-in over a prescribed time length. Three replications were randomly sequenced under each condition, making this a complete 3 × 9 factorial experiment (a total of 81 observations). The data for the study (shown in the table below) were subjected to an ANOVA using SAS. The SAS printout follows. Analyze and interpret the results.

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BURNIN Full Military Specification, A Inspection Levels Reduced Military Specification, B Burn-in (hours) Commercial, C 7.60 7.50 7.67 7.70 7.10 7.20 6.16 6.13 6.21 2 6.54 7.46 6.84 5.85 6.15 6.15 6.21 5.50 5.64 3 6.53 5.85 6.38 5.30 5.60 5.80 5.41 5.45 5.35 4 5.66 5.98 5.37 5.38 5.27 5.29 5.68 5.47 5.84 5 5.00 5.27 5.39 4.85 4.99 4.98 5.65 6.00 6.15 6. 4.20 3.60 4.20 4.50 4.56 4.50 6.70 6.72 6.54 3.66 3.92 4.22 3.97 3.90 3.84 7.90 7.47 7.70 8. 3.76 3.68 3.80 4.37 3.86 4.46 8.40 8.60 7.90 9. 3.46 3.55 3.45 5.25 5.63 5.25 8.82 9.76 9.52