Influential+Observations

Influential Observations (Statistical Model Validation) (GWU EMSE-271)
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An influential observation is one that inordinately influences regression model results. - Lattin

"Data points with large residuals (outliers) and/or high leverage may distort the outcome and accuracy of a regression." - [|Wikipedia] "Observations that have a disproportionate impact on a regression or ANOVA model. Influential observations, also known as unusual observations , are important to identify because they can produce misleading results. For example, a significant coefficient may appear to be nonsignificant. "Influential observations can be: · "Leverage points, which are extreme in the x-direction · "Outliers, which are extreme in the y-direction relative to the fitted regression line · "Both leverage points and outliers - Minitab help.

These are two type of influential observations identified on the Cook's distance page in Wikipedia and Minitabe. Minitab identifies observations with a large standardized residual (which are probably ???).

Question: Are there other types of infulential observations?


 * Sources:**
 * Analyzing Multivariate Data, by James Lattin, Douglas Carroll and Green ([|Amazon]), page 62
 * Cook's distance. (2009, November 4). In //Wikipedia, The Free Encyclopedia//. Retrieved 15:18, December 8, 2009, from []
 * Minitab 15.1.30.0. (c) 2007, Minitab Inc.
 * EMSE 271, Fall 2009