| stacklossDistances {qqtest} | R Documentation |
Mahalanobis squared distances of Brownlee's stack loss plant operation data based only on the explanatory variates (air flow, water temperature, and acid concentration).
Description
Mahalanobis distances were calculated using the mahalanobis R function. Under standard normal theory, these are approximately Chi-squared on 3 degrees of freedom.
Usage
stacklossDistances
Format
A data frame with 21 rows and 2 variates:
- ordinary
Mahalanobis squared distances from the arithemetic mean using the eliptical contours of the sample covariance matrix.
- robust
As with distances, these are Mahalobis squared distances butnow based on robust measures of location and covariance matrix (as determined from the default covRob of the robust package).
Details
with(stacklossDistances, qqtest(robust,dist="chi", df=3)) will show "outliers".
with(stacklossDistances, qqtest(ordinary,dist="chi", df=3)) will show "inliers".
Source
"Statistical Theory and Methodology in Science and Engineering", K.A. Brownlee, (1960, 2nd ed. 1965), Wiley, New York pp. 491-500.