Paper recalls motivation for generalized method of moments (GMM) as well as the idea estimated generalized method of moments. Having demonstrated the danger of underrating the heteroscedasticity of disturbances and recalling Cragg's idea of improvement of estimation under heteroscedasticity, it...

Examples of real data for which various robust methods give rather different estimates of regression model are presented and the reasons of the phenomenon are outlined. Two examples of invented data which enlighten for which kind of data we may expect the diversity of estimates (yielded even -...