compar_r_fisher {graph4lg} | R Documentation |
Compare two correlation coefficients obtained from different sample sizes
Description
The function compares two correlation coefficients obtained from different sample sizes using Z-Fisher transformation.
Usage
compar_r_fisher(data)
Arguments
data |
An object of class
|
Details
The Z-Fisher method consists in computing z scores from the correlation coefficients and to compare these z scores. z scores are computed as follows : Let n1 and r1 be the sample size and the correlation coefficient, z1 = (1/2)*log( (1+r1) / (1-r1) ) Then, a test's statistic is computed from z1 and z2 : Z = (z1-z2) / sqrt( (1/(n1-3)) + (1/(n2-3))) If Z is above the limit given by the alpha value, then the difference between r1 and r2 is significant
Value
An object of class data.frame
with the same columns as 'data'
and 4 columns more : z1, z2 (respective z-scores), Z (test's statistic) and
p (p-value) of the test.
Author(s)
P. Savary
Examples
df <- data.frame(n1 = rpois(n = 40, lambda = 85),
n2 = rpois(n = 40, lambda = 60),
r1 = runif(n = 40, min = 0.6, max = 0.85),
r2 = runif(n = 40, min = 0.55, max = 0.75))
data <- compar_r_fisher(df)