Maynard's Industrial Engineering Handbook, Fifth Edition

Productivity is generally considered to be the ratio of output to input. The concept is simple, yet the ability to measure and analyze productivity often proves to be elusive. Historically, it has been the variety of input that has made it difficult to develop a meaningful measure. Today, we realize that the output side of the equation may be even more difficult. We cannot simply produce for the sake of producing, but rather must produce to meet customer needs. Those needs reflect not only quantity, but also quality and time of delivery.
The potential complexity of the equation may discourage us from even attempting to measure and analyze productivity. However, a common understanding that it is improvements in productivity that lead to increases in our standard...