The Rate of Interest or the Rate of Return: Estimating Intertemporal Elasticity of Substitution

This paper investigates whether the rate of interest such as the Treasury bill rate or the rate of return such as the return on a household portfolio is more relevant to the household’s intertemporal decision making. In a current era, households are diversifiers (to use Tobin’s 1958 term) and hold portfolios of assets rather than a simple loan. A portfolio of assets earns a composite return accounting for capital gains, taxes, and inflation, and rational agents make spending decisions based on expected total returns on a portfolio rather than on the return on a single asset. The total composite measure we use includes financial assets such as stocks and bonds and a real asset, residential housing. In particular, we estimate the intertemporal elasticity of substitution, namely, how a change in the asset or portfolio return affects household’s consumption growth. The estimates obtained using real after-tax composite return are about 0.15-0.3 and are more robust to linear and nonlinear estimations, different consumption measures, and various time periods than those obtained by using individual asset returns such as the Treasury bill rate.