The Gauss-Newton regression (GNR) is widely used to compute Lagrange multiplier statistics. A regression described by Milliken and Graybill yields an exact F test in a certain class of nonlinear models which are linear under the null. This paper shows that the Milliken- Graybill regression is a...

This paper considers the "learning curve" relationship between the aggregate tax rate and the relative size of the hidden economy in New Zealand. Some simple non-linear models are estimated so that the effects of changes in the effective tax rate on the underground economy can be simulated. We...