It changes over time, depending on the expected rate of return on productive assets exchanged among market participants and people$$s time preferences for consumption.Real risk$-$free rate $$r$*$This is the premium added as a compensation for the risk that an investor will not get paid in full.$$This is the premium added to the equilibrium interest rate on a security that cannot be bought or sold quickly enough to prevent or minimize loss.Real risk$-$free rate $$IP $$This is the rate on a Treasury bill or a Treasury bond.$$This is the premium that reflects the risk associated with changes in interest rates for a long$-$term security.$$This is the premium added to the risk$-$free rate that reflects the average sustained increase in the general level of prices for goods and services expected over the security$$s entire life.$$