The importance of measurement error in the cost of capital

Conventional estimates of the impact of taxes on investment may be seriously biased by measurement error in the cost of capital, The existence and size of such error, however has not been documented Using panel data on different types of capital equipment, this paper provides direct evidence of measurement error in the tax component of the cost of capital accounting for about 20 percent of the tax term's variance. Correcting for the error with instrumental variables (IV) estimation shows that taxes significantly affect both prices and investment and that conventional results may be off by as much as a factor of four.