phi2poly {psych} | R Documentation |
Given a phi coefficient (a Pearson r calculated on two dichotomous variables), and the marginal frequencies (in percentages), what is the corresponding estimate of the polychoric correlation?
Given a two x two table of counts
a | b | |
c | d | |
The phi coefficient is (a - (a+b)*(a+c))/sqrt((a+b)(a+c)(b+d)(c+c)).
This function reproduces the cell entries for specified marginals and then calls John Fox's polychor function.
phi2poly(ph, cp, cc)
ph |
phi |
cp |
probability of the predictor – the so called selection ratio |
cc |
probability of the criterion – the so called success rate. |
requires the mvtnorm package
a polychoric correlation
William Revelle
tetrachoric
, polychor.matrix
, Yule2phi.matrix
, phi2poly.matrix
#phi2poly(.3,.5,.5) #phi2poly(.3,.3,.7)