Discussion of the statistical method used in the analysis of thermal evaluation data

Experience has shown that an analysis of test results based on a simple comparison of calculated averages can be misleading. The thermal evaluation literature shows that the insulation systems are compared by a linear relationship between the logarithm of life versus the reciprocal of the absolute temperatures. AIEE #1F describes method to obtain the most probable values of the constants in the equation for the thermal life-line. Often several life-lines are compared graphically without considering whether or not the underlying assumptions for the chosen statistical method is fulfilled. Therefore, in certain cases this advanced analysis can also be misleading.