Heteroscedasticity

Heteroscedasticity (Statistical Model Validation) (GWU EMSE-271)
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"In statistics, a sequence of random variables is **heteroscedastic**, or **heteroskedastic**, if the random variables have different variances.- [|Wikipedia]

This is important because in regression analysis (and elsewhere) one of the important assumptions is that the error terms have the same variance. - Lattin

If this assumption is violated, the model does not have statistical validity.

Look for patterns in error term plots to observe heteroscedasticity.

- [|Wikipedia]


 * Sources:**
 * Heteroscedasticity. (2009, December 5). In //Wikipedia, The Free Encyclopedia//. Retrieved 15:32, December 8, 2009, from []
 * Analyzing Multivariate Data, by James Lattin, Douglas Carroll and Green ([|Amazon]), page 57
 * EMSE 271, Fall 2009