The production function and the Marginal Product of Labor The marginal product of labor is the increase in the amount of output from an additional unit of labor MPL=△Q/△L MPL=(Q2-01)/(L2-L1) H arc Inc items and derived items copyright C 2001 by Harcourt, IncHarcourt, Inc. items and derived items copyright © 2001 by Harcourt, Inc. The Production Function and The Marginal Product of Labor The marginal product of labor is the increase in the amount of output from an additional unit of labor. MPL = Q/L MPL = (Q2 – Q1)/(L2 – L1)