phi: Phi coefficient of correlation
In LatentREGpp: Item Response Theory Implemented in R and Cpp

Description Usage Arguments Details Value References

The phi coefficient is a correlation coefficient applied to dichotomous data. Given a two x two table of counts
| a | b | R1 |
| c | d | R1 |
|—|—|—-|
|C1 | C2| n |
or a vector c(a,b,c,d) of frequencies.

phi(x)

`x`	a 1 x 4 vector or a matrix 2 x 2 of frequencies.

The coefficient phi is calculated from

(ad - bc)/√{p_qp_2q_1q_2}

where

p_i

and

q_i

are the ratios of the dichotomous variables.

the value of the phi coefficient correlation.

Warrens, Matthijs (2008), On Association Coefficients for 2x2 Tables and Properties That Do Not Depend on the Marginal Distributions. Psychometrika, 73, 777-789.

Yule, G.U. (1912). On the methods of measuring the association between two attributes. Journal of the Royal Statistical Society, 75, 579-652.

LatentREGpp documentation built on April 14, 2017, 11:55 a.m.