THE MARGINAL PRODUCT
OF LABOR RECONSIDERED
The data in this study allows for a quantified estimate of the changes in the marginal, average, and total products of labor in a graphical format. The graphical models presented here propose to illustrate the basic features of England and Egypt's economies in the wake of the Black Death. They clarify the changes that took place in both economies and create a more easily conjured relationship with the quantitative data presented thus far. As with all economic models, the structure of the economies as depicted in the graphs has been simplified so that certain basic features can be analyzed and understood. (To state one of the most obvious principles of economics, any model that seeks to depict all aspects of a real economy is no longer a model and is of no value for functional analysis.)
A brief review of the economic concepts that underlie the graphs will be provided first. Not all historians are intimately familiar with the way in which the marginal, average, and total products of labor operate in an economy, and the graphs for Egypt are not typical of those presented in basic macroeconomic texts.
The graphs employ the basic economic concepts of the factors of production (fixed factors and variable factors), the total product, the average product, and the marginal product. A fixed factor is something, such as land or capital, which does not vary in quantity. The variable factor is something, such as labor, which does vary in quantity. The total product (TP) is the total amount of something that is produced in a given period of time. The average product (AP) is the total product divided by the number of units of a variable factor used to produce it. The marginal product (MP) is the change in the total product resulting from the addition of one more unit of the variable product.