Unit, Group, and Composite Depreciation The certified public accountant is frequently called upon by management for advice regarding methods of computing depreciation. Of comparable importance, although it arises less frequently, is the question of whether the depreciation method should be based on consideration of the assets as units, as a group, or as having a composite life. 

(a) Briefly describe the depreciation methods based on treating assets as (1) units and (2) a group or as having a composite life.

(b) Present the arguments for and against the use of each of the two methods.

(c) Describe how retirements are recorded under each of the two methods.
(AICPA adapted)