The Negative Aspects of the Eta Coefficient as an Index of Curvilinearity

Abstract

The objective of this paper is to discuss the eta coefficient and to point out some limitations and misconceptions about the coefficient.
Specifically, we will discuss the fact that; 1) the eta coefficient is a global measure of curvilinearity; 2) the eta coefficient has limited
interpretability; 3) there are a number of other curvilinear relationships that might be of more significance and of more interpretability; 4) these other curvilinear relationships do not suggest nor encourage grouping of data as does the eta coefficient; and 5) these other curvilinear relationships may tend to be more amenable to replication than is the eta coefficient.