The decision-maker is advised to use three dummy variables. The rule of thumb states that it is better to use lesser dummy variables than the categories being investigated. In this case, the categories are four - North, South, East, and West.
This is a statistical term that refers to a factor that is characterized with the value of one or zero in order to explain the presence of absence of an effect that is categorized.
This is used mainly in regression analysis.
See the link below for more about dummy variables:
https://brainly.com/question/4528945