Evaluation: Five Types of Causality

I just came across an interesting table about causality, a critical area of study for evaluators. In this table, Peter Hall (see full citation at end), posits five different types of causality. I have included them here with my own examples as they relate to education.

1) Many causes for the same effect: An increase in x (teacher content knowledge) causes an increase in y (student achievement) in some cases but does not have this same effect in other cases, where y is caused by an entirely different set of causes (an example of such a cause could be increased time spent by student studying). This is one we evaluators see quite often, hence the need for a very thoughtful research design!

2) Cause dependency upon time: An increase in x (years as an educator) is associated with an increase in y (student achievement) at one point in time, but not another. Much research supports the opinion that at least some teachers become less effective as they near retirement, for multiple reasons.

3) Same cause but different outcomes: An increase in x (greater governance by school boards) causes outcome y (increased diversity across all schools in a system) in some cases, but outcome z in other cases (less diversity - more neighborhood schools). This is (unfortunately) happening in Wake County in NC, which is near where I live.

4) Outcomes are the effects of various causes that depend on each other: Outcome y is dependent upon many other variables v, w, and x - whose values are in turn jointly dependent upon each other. I couldn't think of an example for this one. Hall 's example is y (successful wage coordination) depends on the value of many other variables - v (union density), w (social democratic governance), and x (social policy regime) - whose values are in turn jointly dependent on each other

5) Circular causality: Increases in x (student achievement) increase y (student expectations), but increases in y (student expectations) also increase x (student achievement). In this case such causality is a good thing!

Source: Peter A. Hall. 2003. "Aligning Ontology and Methodology in Comparative Research" In J. Mahoney and D. Reuschemeyer, eds. Comparative Historical Analysis in the Social Sciences. New York, NY: Cambridge University Press. Pp.373-404