Jonesmuuttuja

Jonesmuuttuja is a term used in certain statistical and econometric contexts, primarily associated with the work of D. Gale Johnson and his colleagues. It represents a specific type of instrumental variable used in the estimation of demand or supply relationships, particularly when dealing with economic data. The core idea behind a Jonesmuuttuja is to find a variable that influences the price or quantity of a good but is not directly affected by the demand or supply for that same good. This helps to overcome the problem of simultaneity, where the price and quantity are determined jointly by both supply and demand, making direct estimation difficult.

The concept is rooted in the identification problem in econometrics. When estimating a demand curve, for instance, a change in quantity demanded is usually caused by a change in price. However, changes in supply can also cause both price and quantity to change, thus confounding the estimation of the demand relationship. An effective instrumental variable, or Jonesmuuttuja, would be a factor that influences supply (e.g., weather conditions for agricultural products) but does not directly affect consumers' willingness to buy a good at a given price. By using such an instrument, econometricians can isolate the variation in price that is attributable to supply shifts, and then use this to estimate the demand curve. The term itself is less common in mainstream econometric literature compared to the general concept of instrumental variables.