dplR (version 1.6.8)

glk: Calculate Gleichl<U+00E4>ufigkeit

Description

This function calculates the matrix of Gleichl<U+00E4>ufigkeit for a given set of tree-ring records.

Usage

glk(x)

Arguments

x

a data.frame of tree-ring data with records in columns, and years as rows.

Value

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.

Details

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.

References

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.

Examples

# NOT RUN {
library(utils)
data(ca533)
ca533.glk <- glk(ca533)
mean(ca533.glk, na.rm = TRUE)
# }