Estimates of the cost of equity for industries are imprecise. Standard errors of more
than 3.0% per year are typical for both the CAPM and the three-factor model of Fama
and French (1993). These large standard errors arc the result of(i) uncertainty about true
factor risk premiums and (ii) imprecise estimates of the loadings of industries on the risk
factors. Estimates of the cost of equity for firms and projects are surely even less precise.