University of Maryland
Sociology 441: Stratification 

Intervening variables

When we ask: we are trying to understand a relationship between a cause and consequence by identifying other factors that intervene between the cause and the consequence. For instance, if we think that a globalized economy increases inequality in the U.S. because it takes previously well-paid manufacturing jobs and exports them overseas, the we have developed a three variable explanation:
Globalization -> De-industrialization -> Income Inequality

Or if we think the main reason why children from high status families end up in high status occupations themselves is because high status families can guarantee their children more education, then our model is:
Parents' status -> Years of education -> Children's occupational status

We can test these intervening variable explanations by investigating each of the two relationships separately. Thus, if the de-industrialization explanation of the globalization effect is correct, both of the two-variable relationships would have to be true: globalization would have to cause fewer manufacturing jobs and fewer manufacturing jobs would have to cause more income inequality. If either of the two separate relationships turns out to be false, then we have to abandon our de-industrialization explanation.

Much of the activity in social science research is a search for these intervening variables, and testing whether they actually explain the original causal relationships.
 

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Last updated February 11, 2000
comments to: Reeve Vanneman. reeve@umd.edu