kappa2N {GeneTS}R Documentation

Determine the Sample Size from the Degree of Freedom of Correlation Distribution

Description

The degree of freedom kappa of the sample distribution of the correlation coefficient depends both on the sample size N and the number G of investigated variables, i.e. whether simple or partial correlation coefficients are being considered. For G=2 (simple correlation coefficient) the degree of freedom equals kappa = N-1, whereas for arbitrary G (with G-2 variables eliminated in the partial correlation coefficient) kappa = N-G+1 (see also dcor0).

The function kappa2N returns the sample size that corresponds to a given degree of freedom kappa, whereas N2kappa converts sample size to the corresponding degree of freedom.

Usage

kappa2N(kappa, G=2)
N2kappa(N, G=2)

Arguments

kappa degree of freedom
G number of variables (G=2 corresponds to simple correlation)
N sample size

Value

The sample size N corresponding to a given kappa, or the degree of freedom kappa corresponding to a given N.

Author(s)

Juliane Schaefer (http://www.stat.uni-muenchen.de/~schaefer/) and Korbinian Strimmer (http://www.stat.uni-muenchen.de/~strimmer/).

See Also

dcor0, cor0.estimate.kappa.

Examples

# load GeneTS library
library(GeneTS)

# sample sizes corresponding to kappa=7
kappa2N(7)     # simple correlation
kappa2N(7, 40) # partial correlation with 40 variables

# degree of freedom corresponding to N=100
N2kappa(100)
N2kappa(100,40)

[Package GeneTS version 2.3 Index]