Two standard portfolio performance measures are estimated: the Jensen (1968) measure
and the Sharpe (1966) measure. Jensen’s performance measure is the estimated intercept (α)
from, where Rp,t indicates the monthly return on a portfolio of REIT stocks, Rf,t is the monthly return on the (risk free) three month Treasury bill, and Rm,t is the monthly return on a representative “market” portfolio. Jensen’s alpha (α) can be interpreted as a measure of the average excess monthly portfolio return above the monthly market excess return after adjusting for differences in risk. If α is zero, or not significantly different from zero, then the portfolio is performing with a mean monthly rate-of-return, adjusted for risk, that is the mean monthly rate-of-return for the market