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

Level	Individual Fit	Fitted Model
125	89.651	89.654
150	77.769	77.746
175	15.300	15.354

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.