Goodness-of-fit measures - Anderson-Darling (adjusted) statistics for Accelerated Life Testing

The Anderson-Darling (adjusted) statistics are goodness-of-fit measures for the selected probability plots. Anderson-Darling (adjusted) statistics measure the area between the fitted line (based on the chosen model) and the nonparametric step function (based on the plot points). Precisely, the Anderson-Darling (adjusted) statistic is a squared distance that is weighted heavier in the tails of the distribution.

Generally, substantially smaller Anderson-Darling (adjusted) values indicate a better fit. However, when evaluating the model fit, you should always consider the visual results on the probability plots.

Example output

Anderson-Darling (adjusted) Goodness-of-Fit At each accelerating level Individual Fitted Level Fit Model 125 89.651 89.654 150 77.769 77.746 175 15.300 15.354 Standardized Residuals = 36.952 Cox-Snell Residuals = 36.952

Interpretation

For the electronic device data, Anderson-Darling (adjusted) values are provided at each accelerating level for the model, and for the standardized and Cox-Snell residuals. To better assess the model fit, examine the probability plots.