covariance | R Documentation |
It computes the sample covariance in presence of rational subgroups or for individual observations according to Sullivan and Woodall (1996) and Holmes and Mergen (1993)
covariance(x, stat, method, ...)
x |
matrix or array containing the quality characteristics. |
stat |
is the statistics |
method |
is the method used in individual observation case. |
... |
other parameters |
In individual observations case (n = 1) use for default the Sullivan and Woodall (1996) proposal
Edgar Santos-Fernandez
Holmes, D.S., Mergen, A.E.: Improving the performance of T-square control chart. Quality Engineering 5(4), 619-625 (1993)
Sullivan, J.H., Woodall, W.H.: A Comparison of Multivariate Quality Control Charts for Individual Observations. Journal of Quality Technology 28(4) (1996)
# individual case data(bimetal1) covariance(bimetal1, method = "sw") covariance(bimetal1, method = "hm") # rational subgroup case data(carbon1) covariance(carbon1)
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