Which method would not be considered a depreciation method?

Cost allocation is typically used to distribute the costs of an asset or an expense across multiple periods, but it does not specifically relate to the process by which the value of a tangible asset is systematically reduced over time to reflect usage or wear and tear.

On the other hand, methods like straight-line, units of production, and declining balance are all recognized methods of depreciation. Straight-line depreciation allocates an equal amount of depreciation expense each year over an asset’s useful life. Units of production depreciation bases the amount of depreciation on the actual usage or output of the asset. Declining balance depreciation accelerates the depreciation expense, allowing for larger deductions in the earlier years of the asset's life.

Therefore, since cost allocation does not directly pertain to the reduction of an asset's book value over time based on its usage or an established systematic approach, it stands apart from true depreciation methods.