tbrm {dplR} | R Documentation |
This calculates a robust average that is unaffected by outliers.
tbrm(x, C = 9)
x |
a numeric vector |
C |
a constant. C is preassigned a value of 9 according to the
Cook reference below but other values are possible. |
This is a one step computation that follows the Affy whitepaper below see
page 22. This function is called by chron
to calculate a
robust mean. C
determines the point at which outliers are given a
weight of 0 and therefore do not contribute to the calculation of the mean.
C=9 sets values roughly +/-6 standard deviations to 0. C=6 is also used in
tree-ring chronology development. Cook and Kairiukstis (1990) have further
details.
A numeric mean.
Andy Bunn
Statistical Algorithms Description Document, 2002, Affymetrix. p22.
Cook, E. R. and Kairiukstis, L.A. (1990) Methods of Dendrochronology: Applications in the Environmental Sciences. Springer. ISBN-13: 978-0792305866.
Mosteller, F. and Tukey, J. W. (1977) Data Analysis and Regression: a second course in statistics. Addison-Wesley. ISBN-13: 978-0201048544.
tbrm(rnorm(100)) # Compare data(co021) co021.rwi <- detrend(co021,method = "Spline") crn1 <- apply(co021.rwi,1,tbrm) crn2 <- chron(co021.rwi) cor(crn1,crn2[,1])