EXPLAINING GIFT‐EXCHANGE—THE LIMITS OF GOOD INTENTIONS

This paper explores the limitations of intention‐based social preferences as an explanation of gift‐exchange between a firm and a worker. In a framework with one self‐interested and one reciprocal player, gift‐giving never arises in equilibrium. Instead, any equilibrium in a large class of multistage games must involve mutually unkind behavior of both players. Besides gift‐exchange, this class of games also includes moral hazard models and the rotten kid framework. Even though equilibrium behavior may appear positively reciprocal in some of these games, the self‐interested player never benefits from reciprocity. We discuss the relation of these results to the theoretical and empirical literature on gift‐exchange in employment relations.     

Sample size planning for phase II trials based on success probabilities for phase III

In recent years, high failure rates in phase III trials were observed. One of the main reasons is overoptimistic assumptions for the planning of phase III resulting from limited phase II information and/or unawareness of realistic success probabilities. We present an approach for planning a phase II trial in a time‐to‐event setting that considers the whole phase II/III clinical development programme. We derive stopping boundaries after phase II that minimise the number of events under side conditions for the conditional probabilities of correct go/no‐go decision after phase II as well as the conditional success probabilities for phase III. In addition, we give general recommendations for the choice of phase II sample size. Our simulations show that unconditional probabilities of go/no‐go decision as well as the unconditional success probabilities for phase III are influenced by the number of events observed in phase II. However, choosing more than 150 events in phase II seems not necessary as the impact on these probabilities then becomes quite small. We recommend considering aspects like the number of compounds in phase II and the resources available when determining the sample size. The lower the number of compounds and the lower the resources are for phase III, the higher the investment for phase II should be. Copyright © 2015 John Wiley & Sons, Ltd.     

Participation as a means of enhancing the legitimacy of decisions on technology? A sceptical analysis

The legitimacy of technology as a whole, of individual fields of technology, and of concrete decisions on technology has become problematic. Traditional methods and elements for the legitimization of technological development and of the application of technology have been increasingly called into question since the 1980s. There are great expectations in participatory procedures to improving the legitimization of technology decisions. Those expectations, however, might not be justified. In the paper, the hypothesis is proposed that legitimacy can be brought about through participation only under conditions that require the fulfillment of a number of preconditions, which often cannot be regarded as fulfilled. The unavoidable separation between internal communication among the participants and external communication with the nonparticipants turns out to be the fundamental structural characteristic hindering naïve expectations of improving legitimacy by participation.

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Zusammenfassung Die Legitimität von Technik als Ganzem, von einzelnen Technikfeldern und von konkreten Technikentscheidungen ist heute problematisch. Traditionelle Methoden und Elemente für die Legitimierung technischer Entwicklungen und der Anwendung von Technik werden seit den Achtzigerjahren immer mehr in Frage gestellt. Nun setzt man große Erwartungen in partizipatorische Prozeduren, die die Legitimierung von Technikentscheidungen verbessern sollen, Erwartungen, die jedoch möglicherweise nicht gerechtfertigt sind. In diesem Beitrag stellen wir die Hypothese zur Diskussion, dass Partizipation nur unter Umständen zu Legitimität führen kann, die voraussetzen, dass bestimmte Vorbedingungen erfüllt sind, was jedoch oft nicht der Fall ist. Die unvermeidliche Trennung zwischen interner Kommunikation unter den Teilnehmern und externer Kommunikation mit den Nichtteilnehmern erweist sich als das grundlegende strukturelle Merkmal, das der Erfüllung naiver Erwartungen hinsichtlich einer erhöhten Legitimität durch Partizipation im Weg steht.

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Résumé La légitimité de la technologie en tant que tout, de domaines technologiques particuliers et de décisions technologiques concrètes est aujourdhui problématique. Les méthodes et les éléments traditionnels de légitimation des développements technologiques sont depuis les années quatre-vingts de plus en plus remis en question. On fonde à présent de grands espoirs dans les procédures participatives, qui doivent améliorer la légitimation des décisions technologiques, un espoir qui nest cependant peut-être pas justifié. Dans cet article, nous discutons lhypothèse selon laquelle la participation ne peut mener à la légitimité que dans des conditions impliquant à leur tour que certains préalables soient remplis, ce qui nest souvent pas le cas. La séparation inévitable entre la communication interne entre participants et la communication externe avec les nonparticipants savère une caractéristique structurelle fondamentale faisant obstacle à laccomplissement dattentes naïves pour ce qui est dune légitimité accrue par la participation.

     

Progression-free survival in oncological clinical studies: Assessment time bias and methods for its correction

Progression-free survival (PFS) is a frequently used endpoint in oncological clinical studies. In case of PFS, potential events are progression and death. Progressions are usually observed delayed as they can be diagnosed not before the next study visit. For this reason potential bias of treatment effect estimates for progression-free survival is a concern. In randomized trials and for relative treatment effects measures like hazard ratios, bias-correcting methods are not necessarily required or have been proposed before. However, less is known on cross-trial comparisons of absolute outcome measures like median survival times. This paper proposes a new method for correcting the assessment time bias of progression-free survival estimates to allow a fair cross-trial comparison of median PFS. Using median PFS for example, the presented method approximates the unknown posterior distribution by a Bayesian approach based on simulations. It is shown that the proposed method leads to a substantial reduction of bias as compared to estimates derived from maximum likelihood or Kaplan–Meier estimates. Bias could be reduced by more than 90% over a broad range of considered situations differing in assessment times and underlying distributions. By coverage probabilities of at least 94% based on the credibility interval of the posterior distribution the resulting parameters hold common confidence levels. In summary, the proposed approach is shown to be useful for a cross-trial comparison of median PFS.     

DO LAB EXPERIMENTS MISREPRESENT SOCIAL PREFERENCES? THE CASE OF SELF‐SELECTED STUDENT SAMPLES

Social preference research has received considerable attention among economists in recent years. However, the empirical foundation of social preferences is largely based on laboratory experiments with self‐selected students as participants. This is potentially problematic as students participating in experiments may behave systematically different than nonparticipating students or nonstudents. In this paper we empirically investigate whether laboratory experiments with student samples misrepresent the importance of social preferences. Our first study shows that students who exhibit stronger prosocial inclinations in an unrelated field donation are not more likely to participate in experiments. This suggests that self‐selection of more prosocial students into experiments is not a major issue. Our second study compares the behavior of students and participants recruited from the general population in a trust experiment. In general, we find very similar behavioral patterns for the two groups, but nonstudents make significantly more generous repayments suggesting that results from student samples might be seen as a lower bound for the importance of prosocial behavior.     

An Integrated Methodology for Assessment and Selection of the Project Risk Response Actions

In a systematic process of project risk management, after risk assessment is implemented, the risk analysts encounter the phase of assessment and selection of the project risk response actions (RA). As indicated by many researchers, there are less systematic and well-developed solutions in the area of risk response assessment and selection. The present article introduces a methodology including a modeling approach with the objective of selecting a set of RA that minimizes the undesirable deviation from achieving the project scope. The developed objective function comprises the three key success criteria of a project, namely, time, quality, and cost. Our model integrates overall project management into the project risk response planning (P2RP). Furthermore, the proposed model stresses on an equivalent importance for both "risk" and "response." We believe that applying the proposed model helps the project risk analyst in most effective and efficient manner dealing with his or her complicated RA selection problems. The application of the proposed model was implemented in projects in the construction industry in which it showed tremendous time, cost, and quality improvements.     

Visualizing uncertainty in reliability functions with application to aero engine overhaul

Summary.  We propose an approach for estimating the date of lost confidence of jet engines, which are devices with multiple components subject to disruption. A mixed Weibull distribution is estimated from a large data set subject to censoring at various times. Parametric uncertainty is derived analytically and mapped visually onto the functions of use in reliability theory, including the hazard function. We demonstrate the use of the method on a database of disruption times for components in 325 jet engines.