Abstract Two fully quantitative methods are available for calculating the advisability of performing 100% inspection when capital investments must be made to do so. These are the Deming Inspection Criterion (DIC) and the Time-Adjusted Rate-of-Return (TARR), also known as Internal Rate of Return (IRR). In this paper, certain relationships between the two are derived. Methods of handling input data on finances and flaw rates are outlined. Several inspection scenarios derived from actual cases in Ford manufacturing are calculated by both decision theories. The two methods are shown to agree exactly at the break-even point, DIC=1.0 at TARR=0.0, if the financial and flaw data are treated self-consistently in the two methods. Different inspection scenarios lead to families of curves passing through the break-even point. While the DIC dictates 100% inspection when the condition DIC>1.0 occurs, the sets of curves may indicate a low positive TARR in part of this domain. In such cases, use of rigid TARR requirements (e.g., 30% minimum) would lead to a conflict between the two methods of decision theory. Questions of customer loyalty which may impact such decisions are discussed, but not quantified.