A robust model to estimate a firm’s average economic return

Theoretical studies question the ability of financial statement information to provide evidence about a firm’s economic performance, as the mathematical relation between a firm’s accounting and economic returns becomes intractable when economic depreciation is defined endogenously—as a function of the firm’s cash flow stream—and when its internal rate of return (IRR) and investment growth rate have not been constant. This paper derives a new equation, called the average internal rate of return (AIRR) estimation model, in which a firm’s AIRR is estimated as a function of its current-year accounting return, its current-year asset growth rate, a measure of accounting conservatism, and a term that identifies the firm’s historical investment growth rate trend. Because the model allows economic depreciation to be defined exogenously, non-constant returns and growth rates can be aggregated across investment cohorts, allowing a firm’s accounting return to be reconciled to its average economic return. One such exogenous schedule—called competitive market depreciation—is used to illustrate the model’s implications. The AIRR estimation model empowers analysts to identify the direction and magnitude of the potential difference between a firm’s accounting and economic return created by fixed asset depreciation, accounting accruals, and the immediate expensing of intangible assets.