An article by Hoof and Berman (“Statistical Analysis of Power Module Thermal Test Equipment Performance,”

IEEE Transactions on Components, Hybrids, and Manufacturing Technology Vol. 11, pp. 516–520, 1988) describes an experiment conducted to investigate the capability of measurements in thermal impedance (C∘∕w × 100) on a power module for an induction motor starter. There are 10 parts, 3 operators, and 3 replicates. The data are shown in Table P13.2.

(a) Analyze the data from this experiment, assuming that both parts and operators are random effects.

(b) Estimate the variance components using the analysis of variance method.

(c) Estimate the variance components using the REML method. Use the confidence intervals on the variance components to assist in drawing conclusions.