R. A. Meisch (2000) introduces an innovative method for quantifying the reinforcing effectiveness of drugs and other substances. Advantages are that it models the persistence of drug use in humans and its persistence ratios are the same whether responding or consumption is measured. Data indicate that the method is sensitive to factors that affect drug self-administration. The measure's core feature is 'the systematic variation of both reinforcer magnitude and schedule size' (Meisch, 2000, p. 347); however, the method may not be widely used with such extensive parametric analysis. Variation of only reinforcer magnitude (or dose/concentration) seems to produce similar results, and this abbreviated analysis is similar to the behavioral economic analysis of demand. When responding is plotted as a function of unit price (responses/milligram), the peak of the curve (where maximum responding occurs) is a measure of persistence. Further work will determine how these and other measures of reinforcing effectiveness agree.