# Ecological regression

**Ecological regression** is a statistical technique used especially in political science and history to estimate group voting behavior from aggregate data. For example, if counties have a known Democratic vote (in percentage) D, and a known percentage of Catholics, C, then run the linear regression of dependent variable D against independent variable C. This gives D = a + bC. When C = 1 (100% Catholic) this gives the estimated Democratic vote as a+b. When C = 0 (0% Catholic), this gives the estimated non-Catholic vote as a. For example, if the regression gives D = .22 + .45C, then the estimated Catholic vote is 67% Democratic and the non-Catholic vote is 22% Democratic. The technique has been often used in litigation brought under the Voting Rights Act of 1965 to see how blacks and whites voted.[1]

## See also

## References

- Jacob S. Siegel (2002).
*Applied Demography: Applications to Business, Government, Law and Public Policy*. Emerald Group. p. 557. ISBN 9780126418408.

## Further reading

- Brown, Philip J.; Payne, Clive D. (1986). "Aggregate Data, Ecological Regression, and Voting Transitions".
*Journal of the American Statistical Association*.**81**(394): 452–460. doi:10.1080/01621459.1986.10478290. JSTOR 2289235. advanced techniques - King, Gary; Martin Abba Tanner; Ori Rosen (2004).
*Ecological Inference: New Methodological Strategies*. Cambridge University Press. ISBN 9780521542807. - Kousser, J. Morgan (1973). "Ecological Regression and the Analysis of past Politics" (PDF).
*Journal of Interdisciplinary History*.**4**(2): 237–262. doi:10.2307/202265. JSTOR 202265. with guide to the literature