Causal model

A causal model can be defined as a representation of the relationships between/among variables. It is based on the assumption that one variable (Y) is a mathematical function of another (X). The former is called the dependent and the latter the independent variable. This model can be portrayed using a path diagram – a pictorial representation of hypothetical relationships between/among variables. Generally, researchers are interested in the sign, strength, and significance of these relationships.

Although causality implies some correlation between two variables, this does not imply causal linkage between them, because coincidences or the existence of other variable(s) exerting effects on them can explain such correlations. In other words, significant correlation is a necessary but not a sufficient condition for causality. Strictly speaking, one would say that X causes Y when an increase of the former results in an increase of the latter, ceteris paribus.

In addition, it is generally...