psych (version 1.6.12)

fisherz: Transformations of r including Fisher r to z and z to r and confidence intervals

Description

Convert a correlation to a z or t, or d, or chi score or z to r using the Fisher transformation or find the confidence intervals for a specified correlation. r2d converts a correlation to an effect size (Cohen's d) and d2r converts a d into an r. g2r converts Hedge's g to a correlation. t2r converts a t test to r, r2t converts a correlation to a t-test value. chi2r converts a chi square to r, r2chi converts it back.

Usage

fisherz(rho)
fisherz2r(z)
r.con(rho,n,p=.95,twotailed=TRUE)
r2t(rho,n)
r2d(rho)
d2r(d)
t2r(t,df)
g2r(g,df,n)
chi2r(chi,n)
r2chi(rho,n)

Arguments

rho

a Pearson r

z

A Fisher z

n

Sample size for confidence intervals

df

degrees of freedom for t, or g

p

Confidence interval

twotailed

Treat p as twotailed p

d

an effect size (Cohen's d)

g

An effect size (Hedge's g)

t

A student's t value

chi

A chi square

Value

r corresponding to z (fisherz2r) \ lower and upper p confidence intervals (r.con) \ t with n-2 df (r2t) r corresponding to effect size d or d corresponding to r.

Examples

cors <- seq(-.9,.9,.1)
zs <- fisherz(cors)
rs <- fisherz2r(zs)
round(zs,2)
 n <- 30
 r <- seq(0,.9,.1)
 rc <- matrix(r.con(r,n),ncol=2)
 t <- r*sqrt(n-2)/sqrt(1-r^2)
 p <- (1-pt(t,n-2))/2
 r.rc <- data.frame(r=r,z=fisherz(r),lower=rc[,1],upper=rc[,2],t=t,p=p)
 round(r.rc,2)

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