This function calculates the matrix of Gleichl<U+00E4>ufigkeit for a given set of tree-ring records.
glk(x)
a data.frame
of tree-ring data with records in
columns, and years as rows.
A matrix
with the Gleichl<U+00E4>ufigkeit for
all possible combinations of records. If two curves have less than 3
years of overlap, Gleichl<U+00E4>ufigkeit cannot be
computed, and NA
is returned.
Gleichl<U+00E4>ufigkeit is a classical agreement
test based on sign tests (Eckstein and Bauch, 1969). This function
implements Gleichl<U+00E4>ufigkeit as the pairwise
comparison of all records in data set, and thus returns a matrix whose
upper triangle reports the Gleichl<U+00E4>ufigkeit
of each possible combination of records. The global
Gleichl<U+00E4>ufigkeit can be calculated as
mean(glk(x), na.rm = TRUE)
. This implementation improves
the original formulation inasmuch as the case of neighbouring
identical measurements in the same years is accounted for. Here, it is
treated as full agreement, in contrast to only partial agreement in
the original formulation.
Eckstein, D. and Bauch, J. (1969) Beitrag zur Rationalisierung eines dendrochronologischen Verfahrens und zur Analyse seiner Aussagesicherheit. Forstwissenschaftliches Centralblatt, 88(1), 230<U+2013>250.
Schweingruber, F. H. (1988) Tree rings: basics and applications of dendrochronology. Kluwer Academic Publishers, Dordrecht, Netherlands, 276 p.
# NOT RUN {
library(utils)
data(ca533)
ca533.glk <- glk(ca533)
mean(ca533.glk, na.rm = TRUE)
# }
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