This thesis is a contribution to consumption analysis and to retail analysis in the agrofood sector. It lies both within the theoretical scope of the econometrics of demand and the vertical relationships in Industrial Organization. The first part is based on the example of wine consumption. The aim is to understand, on the statistical level, the wide range of estimated price and income elasticities. Using meta-analysis, the author show how the diverse results obtained vary according to the socio-economic characteristics of the studied population, the type of data, and the technologies of modelling retained by the author. After having noted that the characteristics of wines influence the estimates of income elasticities, she proposes a protocol of experimental economics, allowing measurement of the willingness to pay for labels of origin. The second part of the thesis is interested in the improvement of the willingness to pay by retailers. First, the author show how it is possible to consider selective retail of the products by efficient retailers which provide promotional efforts. While being based on a study of the private label in the fresh product sector, the final chapter of this thesis studies the possibility for retailers to improve the quality of the products and the effects induced by such a strategy on agrofood sector economics.