Depreciation Rates for the Productivity Accounts - ARCHIVED

This paper generates depreciation profiles for a diverse set of assets based on patterns of resale prices and retirements. In doing so, it explores the sensitivity of estimates of the growth in capital stock and capital services to alternate estimates of depreciation.

In the first instance, survival analysis techniques are used to estimate changes in valuation of assets over the course of their service life. In the second instance, a two-step procedure is utilized that first estimates the discard function for used assets (assets discarded at zero prices) and then uses the resulting estimates to correct for selection bias that arises when just positive used-asset prices are employed to estimate age-price profiles to produce depreciation rates. For the third method, a discard function and an asset efficiency function are jointly specified and estimated.

These three different methods produce depreciation profiles that follow convex patterns. Accelerated profiles are apparent for many individual assets in the machinery and equipment and structures classes.

We also compare the ex post estimates of length of life that are based on outcomes to ex ante expected lives and find they are much the same. We therefore choose ex ante lives along with information from the ex post rates on the rate of decline in an asset's value to generate a set of depreciation rates for use in the productivity accounts.

We then use our depreciation model to produce estimates of the growth in capital stock and capital services over the 1961 to 1996 period. We find that the resulting estimates of capital stock and capital services are quite similar to those previously produced.