Existence and specific characters of rentiers: a savers-spenders theory approach

Summary. Using the savers-spenders theory developed by Mankiw (2000, AER), we propose microfoundations to the existence of rentiers in macroeconomic growth models. From an OLG model which acknowledges the great heterogeneity of consumer behavior apparent in the data, we capture the dynamic considerations of potential rentiers as a natural consequence of intertemporal utility maximization and we analyze realistic characteristics (proportion, wealth, propensity to save) of rentiers.JEL Classification Numbers: E13, D64, J22.This paper is adapted from the fourth chapter of my Ph.D Thesis. Then, I thank Alain VENDITTI, my Ph.D Supervisor and Antoine dAUTUME and Pierre PESTIEAU my Ph.D Referees. Earlier version of this paper were presented at the International conference: New perspectives on (un)stability: the role of heterogeneity at Marseille, June 7-9, 2001 and at the X-th Spring School of the Associated European Laboratory (CNRS-FNRS/CORE-GREC-GREQAM) at Aix, 2001. I thank conference participants, in particular Olivier CHARLOT, Christian GHIGLINO, Kiminori MATSUYAMA and Philippe MICHEL for suggestions, helpful comments and discussions. I also thank a referee of this journal for his constructive comments.     

Estimation of slowly decreasing Hawkes kernels: application to high-frequency order book dynamics

We present a modified version of the non parametric Hawkes kernel estimation procedure studied in Bacry and Muzy [arXiv:1401.0903, 2014] that is adapted to slowly decreasing kernels. We show on numerical simulations involving a reasonable number of events that this method allows us to estimate faithfully a power-law decreasing kernel over at least six decades. We then propose a eight-dimensional Hawkes model for all events associated with the first level of some asset order book. Applying our estimation procedure to this model, allows us to uncover the main properties of the coupled dynamics of trade, limit and cancel orders in relationship with the mid-price variations.     

Modeling of the clinical and economic impact of a risk-sharing agreement supporting a treat-to-target strategy in the management of patients with rheumatoid arthritis in France

Objectives: To evaluate the cost-effectiveness of a Treat-to-Target strategy with certolizumab pegol in patients with rheumatoid arthritis in the context of a pay-for-performance agreement in which medication costs are refunded in case of discontinuation during the first 3 months of treatment.

Methods: The Treat-to-Target strategy consisted of a systematic switch to second-line tumor necrosis factor (TNF)α inhibitor in case of an unmet ACR50 response at 3 months compared to current routine clinical practice. A reference cohort treated first-line with certolizumab pegol according to current practice without systematic switching was considered as the comparator. A decision-tree model was constructed to estimate clinical outcome (health assessment questionnaire-disability index or HAQ-DI score), time spent in ACR50 response (ACR 50), and direct costs of treatment over a 2-year period. HAQ scores were derived from American College of Rheumatology 50 (ACR50) responses. All TNFα inhibitors were assumed to have equivalent efficacy and tolerability. Costs were estimated at 2013 French retail prices (date of the pay-for-performance agreement).

Results: The mean duration of an ACR50 response was 1.23 years in the Treat-to-Target strategy certolizumab pegol cohort vs 0.98 years in the reference cohort, resulting in a mean gain in HAQ at 24 months of 0.117. The Treat-to-Target strategy with a mix of TNFα inhibitors as second-line therapy was more expensive than the reference strategy in absolute terms, but this difference was entirely offset by the pay-for-performance agreement. The Treat-to-Target strategy was, thus, cost-neutral over a 2-year period after the payback of CZP cost for patients not achieving the target at 3 months.

Conclusions: In the context of a pay-for-performance agreement, the management of patients with rheumatoid arthritis using a Treat-to-Target strategy with certolizumab pegol in first line is dominant compared to standard use of this drug in the French setting in 2013.     

Market impact as anticipation of the order flow imbalance

In this paper, we assume that the permanent market impact of metaorders is linear and that the price is a martingale. Those two hypotheses enable us to derive the evolution of the price from the dynamics of the flow of market orders. For example, if the market order flow is assumed to follow a nearly unstable Hawkes process, we retrieve the apparent long memory of the flow together with a power law impact function, which is consistent with the celebrated square root law. We also link the long memory exponent of the sign of market orders with the impact function exponent. One of the originalities of our approach is that our results are derived without assuming that market participants are able to detect the beginning of metaorders.     

The failure of Ricardian equivalence under dynastic altruism

This paper investigates the theoretical accuracy of the Barro [Barro, R.J., 1974. Are government bonds net wealth? Journal of Political Economy, 82, 1095–1117] debt neutrality proposition. We first identify a discrepancy between the transversality condition of a social planning problem and the one of altruistically linked overlapping generations. Then, this discrepancy is exploited to construct public debt policies which affect the competitive equilibrium allocation even when bequests are strictly positive in all periods: a violation of Ricardian equivalence.     

Introduction to inequality and risk

This introduces the symposium on inequality and risk.     

Towards a New Flashmob Unionism: The Case of the Fight for 15 Movement

Unionism renewal has been described as a hybridization process between ‘old’ and ‘new’ logics. Understanding how these two potentially conflicting logics might be combined, however, has so far received little attention. Through the study of the Fight for 15 (FF15) movement, we investigate how the old ‘collectivist’ logic of action-oriented unions and the new ‘connectivist’ logic are being hybridized. To do so, we develop a mixed-methods approach that combines interviews with Twitter data. We evidence three mechanisms through which the collectivist and connectivist logics are being hybridized, namely, imbrication, camouflage and cumulation. We suggest to name ‘flashmob unionism’ the hybrid logic of FF15, characterized by apparently spontaneous mobilizations, a loosely co-ordinated organization, a personalized communication and online virality.     

Are Consumers International? A Study of CSR,Cross-Border Shopping,Commitment and Purchase Intent among Online Consumers

The purpose of this study is to investigate purchase intent in online marketplaces as an international phenomenon. A profile of the international online consumer is established, taking into account factors such as indicators of socio-economic development of their home countries. A structural model is analyzed using LISREL, testing the importance of CSR, the propensity to buy from international online vendors and commitment with purchase intent as the dependent variable. A cross-national dataset of 804 respondents from 57 countries is analyzed, showing that CSR activities alone do not increase purchasing intent, but they do when mediated by commitment.     

Existence of equilibrium in an OLG model with production and altruistic preferences

Summary. This note deals with the existence and uniqueness of a non-trivial steady-state equilibrium in an overlapping generations (OLG) model with productive capital and altruistic agents. We establish a necessary and sufficient condition for operative bequests which extends Abel (1987) and Weil (1987). Interestingly, we prove that the OLG model with production and altruistic agents always experiences a non-trivial steady-state equilibrium. Received: July 16, 1998; revised version: January 29, 1999