The Relationship Between the Phi Coefficient and the G Index1

Abstract
The value of the phi coefficient (Φ) cannot, in general, be uniquely determined from the G index. Its value is shown to obey the inequalities G-1/3+ G ≤ Φ ≤ 1+ G/3- G if -1 < G < 1 When G equals -1 or 1 so does Φ. As a consequence of this Φ is too unstable over item reflection when used as a measure of similarity between individuals. G is a more suitable choice.

This publication has 1 reference indexed in Scilit: