Non parametric specification has become vital recipe in estimation of the Engel Curves. This book provide an introduction to the method and the more flexible functional form of the Engel curves and argue of the complexity nature of the household budget data in framework of gender bias in consumption pattern. This book presents the parametric misspecification of the Engel Curves by an alternative specification of Non parametric functional form. The focus also is on the relationship between demographic structures of the household and the way in which it spends its resources. The book uses the Working-Leser model, the Semi parametric and recently Deaton's approaches to examine bias in consumption pattern. This is a key text for graduate students in economics and econometrics and valuable resource for researchers in academics.