Articles

Microcomputations as Micropayments in Web-based Services

G. O. KARAME, A. FRANCILLON, V. BUDILIVSCHI, S. CAPKUN, V. CAPKUN

ACM Transactions on Internet Technology

May 2014, vol. 13, n°3

Departments: Accounting & Management Control, GREGHEC (CNRS)

http://dl.acm.org/citation.cfm?id=2611526&dl=ACM&coll=DL&CFID=790735117&CFTOKEN=32190012


In this article, we propose a new micropayment model for nonspecialized commodity web-services based on microcomputations. In our model, a user that wishes to access online content (offered by a website) does not need to register or pay to access the website; instead, he will accept to run microcomputations on behalf of the service provider in exchange for access to the content. These microcomputations can, for example, support ongoing computing projects that have clear social benefits (e.g., projects relating to medical research) or can contribute towards commercial computing projects. We analyze the security and privacy of our proposal and we show that it preserves the privacy of users. We argue that this micropayment model is economically and technically viable and that it can be integrated in existing distributed computing frameworks (e.g., the BOINC platform). In this respect, we implement a prototype of a system based on our model and we deploy our prototype on Amazon Mechanical Turk to evaluate its performance and usability given a large number of users. Our results show that our proposed scheme does not affect the browsing experience of users and is likely to be used by a non-trivial proportion of users. Finally, we empirically show that our scheme incurs comparable bandwidth and CPU consumption to the resource usage incurred by online advertisements featured in popular websites

A primal condition for approachability with partial monitoring

S. MANNOR, V. PERCHET, G. STOLTZ

Journal of Dynamics and Games

July 2014, vol. 1, n°3, pp.447-469

Departments: Economics & Decision Sciences, GREGHEC (CNRS)

Keywords: Approachability theory, Online learning, Imperfect monitoring, Partial monitoring, Signals


In approachability with full monitoring there are two types of conditions that are known to be equivalent for convex sets: a primal and a dual condition. The primal one is of the form: a set C is approachable if and only all containing half-spaces are approachable in the one-shot game. The dual condition is of the form: a convex set C is approachable if and only if it intersects all payoff sets of a certain form. We consider approachability in games with partial monitoring. In previous works [5,7] we provided a dual characterization of approachable convex sets and we also exhibited efficient strategies in the case where C is a polytope. In this paper we provide primal conditions on a convex set to be approachable with partial monitoring. They depend on a modified reward function and lead to approachability strategies based on modified payoff functions and that proceed by projections similarly to Blackwell's (1956) strategy. This is in contrast with previously studied strategies in this context that relied mostly on the signaling structure and aimed at estimating well the distributions of the signals received. Our results generalize classical results by Kohlberg [3] (see also [6]) and apply to games with arbitrary signaling structure as well as to arbitrary convex sets

A structural approach to handling endogeneity in strategic management: the case of RBV

A. NANDIALATH, J. DOTSON, R. DURAND

European Management Review

April 2014, vol. 11, n°1, pp.47-62

Departments: Strategy & Business Policy, GREGHEC (CNRS)

Keywords: Resource based view, Bayesian modeling, Endogeneity, Structural modeling, Competitive strategy


In this paper we posit that the lack of consensus about empirical tests of resource based view (RBV) could be the result of endogenous resource picking on the part of firms. If resources are endogenously selected, regression based methods that examine their connection to firm performance will be mis-estimated. We show that traditional remedies for endogeneity do not resolve this problem when returns to resources are heterogeneous (as theorized under RBV) and when managers act with at least partial knowledge of the expected, idiosyncratic return (as theorized under the strategic factor market hypotheses). As such, we develop a Bayesian approach that solves this endogeneity problem by directly incorporating resource picking into the modeling framework. We illustrate the validity of our approach through the use of a comprehensive simulation study and show that our proposed approach outperforms traditional linear models (including traditional cures of endogeneity and unobserved heterogeneity) under a variety of conditions. Our findings suggest that: (1) research in strategy requires a more careful and deeper understanding of potential sources of endogeneity and (2) the use of Bayesian methods in management can help develop more theoretically motivated empirical approaches to hypothesis testing

Acts, Persons, and Intuitions: Person-Centered Cues and Gut Reactions to Harmless Transgressions

E. L. UHLMANN, L. ZHU

Social Psychological and Personality Science

April 2014, vol. 5, n°3, pp.279-285

Departments: Management & Human Resources

Keywords: Person-centered moral judgments, Moral intuitions, Social intuitionist model, Moral dumbfounding, Informational value, Act-person dissociations


Negative gut reactions to harmless-but-offensive transgressions can be driven by inferences about the moral character of the agent more so than condemnation of the act itself. Dissociations between moral judgments of acts and persons emerged, such that participants viewed a harmless-but-offensive transgression to be a less immoral act than a harmful act, yet more indicative of poor moral character. Participants were more likely to become "morally dumbfounded'' when asked to justify their judgments of a harmless-but-offensive act relative to a harmful act. However, they were significantly less likely to become morally dumbfounded when asked to justify character judgments of persons who engaged in the harmless-but-offensive transgression, an effect based in part on the information-rich nature of such behaviors. Distinguishing between evaluations of acts and persons helps account for both moral outrage over harmless transgressions and when individuals are (and are not) at a loss to explain their own judgments

An Empirical Investigation of the Impact of Audit and Auditor Characteristics on Audit Performance

W. ALISSA, V. CAPKUN, T. JEANJEAN, N. SUCA

Accounting Organizations and Society

October 2014, vol. 39, n°7, pp.495-510

Departments: Accounting & Management Control, GREGHEC (CNRS)

Keywords: Auditor effort, Auditor experience, Task complexity, Auditor performance, Tax audits

http://ssrn.com/abstract=2458850


We use a unique and confidential database of 15,392 tax audits performed by the Croatian Tax Administration during the 2002-2006 period to examine the impact of task complexity, auditor experience, and auditor effort on audit performance. We provide external validation to prior experimental and analytical research showing that task complexity decreases while auditor experience and effort increase audit performance. We also extend this literature by examining the roles of task complexity and experience in moderating the impact of the effort on audit performance. We find that task complexity mitigates, while experience enhances the positive relationship between auditor effort and performance. However, we also find that auditor experience reinforces the positive effect of auditor effort on performance to a greater degree when complexity is high. Taken together, our findings provide new evidence on how audit and auditor characteristics impact audit performance, and new insight into how task complexity and auditor experience separately and jointly moderate the impact of auditor effort on performance


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