Health Services Research (HSR) Methods
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Perfect Collinearity
Related Terms: Dummy Variable; Dummy Variable Trap; Multicollinearity

An exact linear relationship between two independent variables included in a regression model.

1) A regression model includes separate indicator variables for female and male as independent variables. Since there is an exact linear relationship between these two variables (female is equal to 1-male), the model parameters cannot be estimated.


Further Reading
Kennedy, P. 1998. A Guide to Econometrics, Cambridge, MA: The MIT Press.

Greene, L.. 2003. Econometric Analysis, 5th ed., Upper Saddle River, NJ: Prentice Hall.

Goldberger, A.S.. 1991. A Course in Econometrics, Cambridge: MA: Harvard University Press.

Bohrnstedt, G.W. and D. Knoke. 1994. Statistics: A Tool for Social Data Analysis, Itasca, IL: Peacock Publishers.