The prison camp is a microcosm of a society, and it has institutions which facilitate and constrain the economic activities. The dynamics of the environment and the utility maximizing behavior of the individuals create supply/demand fluctuations. There are behaviors and events, which result in the change in the endogenous variable (price) and cause a shift along the supply/demand curves. Furthermore, there are behaviors and events which affect the exogenous variables, which led to similar market shifts. Listed below are a few examples of the events and behaviors that illustrate this point.
Influx of new prisoners: This phenomenon lead to a significant shift in the supply/demand curve because the prisoners arriving tended to be extremely hungry, and there was already a limited supply, barely enough to meet the sudden spike in demand.
Good/bad news: Macro-level war news changed people's behaviors and consumption patterns. For instance upon receiving good news about the war the prisoners used to discount the need to ration their reserves and engage in consumption pattern which depleted the supplies.
This behavior led to significant increase in the demand in the next period.
Seasonality: Seasonal changes resulted in a shift in the supply/demand curves. For example, during winter the demand for coca went up and the demand for its substitution product went down.
Invention: This leads to disruptive change and shifts the supply/demand curve. For example, in the prison, the discovery that raisins and sugar could be turned into alcohol led to significant change in the perceived value and the corresponding demand and supply for raisins.
Substitution effect: When the price of a product goes up, it shifts the demand for its substitute product. For example, in the prison as price of German Margarine increased, demand for Canadian Butter increased.
Bio:Radford, R. A.. "The Economic Organisation of...