Before revision: Quasi-hyperbolic approximation The "quasi-hyperbolic" discount function , proposed by Laibson (1997), approximates the hyperbolic discount function above in discrete time by and where β and δ are constants between 0 and 1; and again D is the delay in the reward, and fQH(D) is the discount factor .
After revision: Quasi-hyperbolic approximation The "quasi-hyperbolic" discount function , proposed by Laibson (1997), approximates the hyperbolic discount function above in discrete time by and where β and δ are constants between 0 and 1; and again D is the delay in the reward, but now it takes only integer values(sometimes called "beta-delta discounting") .