Interaction Terms in Nonlinear Models

Interaction terms in nonlinear models.

OBJECTIVES To explain the use of interaction terms in nonlinear models. STUDY DESIGN We discuss the motivation for including interaction terms in multivariate analyses. We then explain how the straightforward interpretation of interaction terms in linear models changes in nonlinear models, using graphs and equations. We extend the basic results from logit and probit to difference-in-differenc...

Testing hypotheses about interaction terms in nonlinear models

Incomplete Draft Do Not Cite Interaction Terms in Nonlinear Models

Although applied economists often estimate interaction terms to infer how the effect of one independent variable on the dependent variable depends on the magnitude of another independent variable, most researchers misinterpret the coefficient in nonlinear models. The magnitude of the interaction effect does not equal the coefficient on the interaction term, can be of opposite sign, and is cond...

Testing Hypotheses About Interaction Terms in Nonlinear Models

A recent, widely discussed contribution to econometric practice by Ai and Norton (2003) has proposed an approach to analyzing interaction effects of variables in nonlinear models. The authors focus attention on a binary choice (logit) model, though their results are easily extended to other nonlinear models. The main result of the study applies to a model that contains an interaction term, such as

Fuzzy Observers for Takagi-Sugeno Models with Local Nonlinear Terms

The paper deals with the problem of nonlinear fuzzy observers for a class of continuous-time nonlinear systems, represented by Takagi-Sugeno models with local nonlinear terms. On the basis of the Lyapunov stability criterion and incremental quadratic inequalities, the sufficient LMI design conditions are outlined. Numerical example is given to illustrate the procedure and to validate the perfor...