Production with one variable input,labor,can be usefully described in terms of the average product of labor (which measures output per unit of labor input),and the marginal product of labor(which measures the additional output as labor is increased by 1 unit).❑ Production with one variable input, labor, can be usefully described in terms of the average product of labor (which measures output per unit of labor input), and the marginal product of labor(which measures the additional output as labor is increased by 1 unit)