"Introduction As is stated in AIEE No. 1@ accelerated life tests are recommended to determine the probable life expectancy of electrical insulating materials and of complete insulation systems under different conditions of service. Recommended procedures for conducting life tests at various temperatures to accelerate insulation degradation are outlined in AIEE ID and IE. AIEE publications Nos. 57@ 65@ 510 and 511 are examples of test procedures developed for this purpose. After life data from such tests have been obtained at different temperatures@ the problem is to evaluate the resultant data so that the life expectancy of insulation can be estimated. For this purpose@ life expectancy is considered as a function of temperature. The most probable form of this relationship@ and its reliability@ are determined by the statistical procedures outlined herein. It has been found that the Arrhenius equation@ which describes the temperature dependence of the ""velocity coefficient"" of chemical reactions@ can be used to approximate the relationship between insulation life and temperature. This equation indicates that the logarithm of insulation life should be a linear function of the reciprocal of absolute temperature. Regression analysis is the technique used to determine the best estimate of the slope and intercept of the straight line that relates the logarithm of insulation life to the reciprocal of absolute temperature."