This is measured as the ratio of the rate of depreciation versus prior year. A slower rate of depreciation (DEPI greater than 1) may means that the firm is revising useful asset life assumptions upwards, or adopting a new method that is income friendly.
Declining depreciation rates could indicate understated depreciation as a means of manipulating earnings.
A DI greater than 1.0 suggests that the rate of depreciation has slowed, thus indicating changes to revised upwards the estimated useful lives of its larger assets or new methods. Therefore, on can expect a positive relation between DI and the probability of earnings manipulation.