El rol de los ingresos en los modelos de elección discreta. Su importancia en los proyectos de evaluación

The research in discrete choice models with foundations in microeconomic principles has developed a framework for the detection of income effect for estimating demands or even welfare measurement with particular emphasis in transport sector. However, these theoretical researches have not been frequeltly used in the praxis of apparaisal projects. The aggregation of benefits across individuals leads to require sophisticated tools so as to avoid a mis-specification of incomes in models. This latter may potentially distort outcomes and unintentionally conduct to non-optimal decisions that turns critical in large investments. The present paper seeks to stand out the importance of considering the income effect in appraisal projects. For this purpose, on the basis of discrete choice theory, several models has been tested by using the multinomial logit models. The dataset collected comes from an urban transport survey Lima Metropolitan in 2004. The models have sought to detect the presence of income effect, thus by assuming an income tier. It has been found the individuals surveyed in the study can be classified in statistical terms into two representative income-groups. Then, by following the Jara-Diaz and Videla (1989), shows that the marginal utility of income decreases with income and these are statistically different when are calculated among groups.