Note on the Assumptions Underlying Holzinger's h2 Statistic
Joan May · Journal of Mental Science · 1951
Holzinger set up his equations to show the combination of the factors—nature (A), nurture (B), and error(E)—which go to make up a score obtained by a particular twin on a particular test. If iX1 and iX2 are the twins in an identical pair and fX1 and fX2 are the twins in a fraternal pair then: —