Abstract: This paper undertakes a study about the "zero" option in conjoint analysis. The "zero" option relates to the no choice of products presented to individuals within the frame of a survey. This no choice embeds two distinct concepts, the refusal and the conflict. The first represents the inappreciation of products, while the second is defined by the preference and choice uncertainty. This work proposes a new econometric specification of the no choice by assuming a mix of utilities maximisation and ordered response models. This mix only associates utilities with products and compares them to the "zero" option thresholds. These comparisons lead to no choice situations without linking utilities to refusal and conflict. A study on the Video on Demand market has been conducted. The results are obtained by applying a bayesian approach in the case of individual models, and the maximum likelihood in the case of aggregate models. The estimates fit the reality and the significance of the refusal and the conflict demonstrates the importance of these variables in the decision making process. Article on SSRN
Abstract: This study adopts a quasi-experimental design to estimate the impact on security of the introduction of community policing in a district of the city of Mbujimayi, Democratic Republic of Congo. The authors suggest that security is best captured by a multidimensional index from which they derive a series of outcome indicators such as the incidence of insecurity, the vulnerability to insecurity, or the severity of insecurity. The data originate from representative surveys conducted at pre- and post-treatment times in the pilot and control districts. The main impact estimates are calculated using the Difference-in-Difference (DiD) approach. The DiD estimates are cross-checked with DiD estimates obtained with propensity score matched data to control for the selection bias inherent to quasi-experimental designs. After a year of treatment, the short-term effect of community policing is found to be efficient based on the security indicators and consistently so across approaches. The study finds that community policing impacted strongly on the two dimensions of security: access to policing services and police legitimacy. The effect of community policing is found however to be significantly higher for men than for women and to have had no or only marginal impact on younger women who remained vulnerable to insecurity even after treatment. Article on Police Practice and Research