On estimating the reliability after sequentially estimating the mean: The exponential case

Sequential estimation problems for the mean parameter of an exponential distribution has received much attention over the years. Purely sequential and accelerated sequential estimators and their asymptotic second-order characteristics have been laid out in the existing literature, both for minimum risk point as well as bounded length confidence interval estimation of the mean parameter. Having obtained a data set from such sequentially designed experiments, the paper investigates estimation problems for the associatedreliability function. Second-order approximations are provided for the bias and mean squared error of the proposed estimator of the reliability function, first under a general setup. An ad hoc bias-corrected version is also introduced. Then, the proposed estimator is investigated further under some specific sequential sampling strategies, already available in the literature. In the end, simulation results are presented for comparing the proposed estimators of the reliability function for moderate sample sizes and various sequential sampling strategies.     

A General Method of Deriving the Inefficiencies of Banks from a Profit Function

This article develops a new method of estimating inefficiencies in joint production and shows that unlike the approaches utilized in the previous studies of inefficiency, this method maintains a consistent relationship between the error term of a profit function and the error terms of its price derivatives. A useful by-product of the method is a proof of a Hotelling-like lemma that relates stochastic input demand and output supply functions to stochastic profit functions. While the previous studies fit a single frontier to data on all firms, this paper estimates a frontier unique to every observed firm to allow each one to have a different potential of achieving maximal levels of profit. The new method is applied in the analysis of annual data, 1984–1989, for U.S. commercial banks. Both the analytical and numerical results of the paper show that the residual that the previous studies attribute to inefficiency includes the effects of excluded variables and of inaccuracies in the specified functional forms. Once accurate estimates of these effects are subtracted from the residual, the distortions in the measured inefficiencies should be considerably reduced. Consequently, this article considers how such estimates might be obtained.     

The “Iron Law of Paternalism” in Employee Grievances and Arbitration? A Comparison of Disciplinary and Nondisciplinary Cases

In the criminology literature, the iron law of paternalism suggests that women receive less serious sanctions in the judicial system. This examination of three years of grievance outcomes (n= 1216) and arbitration outcomes (n= 1146) tests this iron law in the context of organizational disciplinary and dispute resolutions. These data, across several levels of outcomes (win, lose, compromise), controlling for the severity of grievances (disciplinary/nondisciplinary) and arbitrations (termination/nontermination) provide no support for the paternalistic thesis. Moreover, we find no support for the paternalistic thesis with regard to either the incidence or length of suspensions as a function of gender.     

Testing for unit roots in time series models with non-stationary volatility

Many of the key macro-economic and financial variables in developed economies are characterized by permanent volatility shifts. It is known that conventional unit root tests are potentially unreliable in the presence of such behaviour, depending on a particular function (the variance profile) of the underlying volatility process. Somewhat surprisingly then, very little work has been undertaken to develop unit root tests which are robust to the presence of permanent volatility shifts. In this paper we fill this gap in the literature by proposing tests which are valid in the presence of a quite general class of permanent variance changes which includes single and multiple (abrupt and smooth-transition) volatility change processes as special cases. Our solution uses numerical methods to simulate the asymptotic null distribution of the statistics based on a consistent estimate of the variance profile which we also develop. The practitioner is not required to specify a parametric model for volatility. An empirical illustration using producer price inflation series from the Stock–Watson database is reported.     

A critical test of the choice questionnaire for collecting informed public opinions

In the Choice Questionnaire (Neijens et al. 1992) respondents have to choose between several policy options. Within this questionnaire they are provided with information about the consequences of each option. Until now, only indirect evidence as to whether or not respondents base their preferences on the information provided was available and plausible alternative explanations for the Choice Questionnaire's effect could not be ruled out. In the present study, we demonstrate that Choice Questionnaire respondents do base their preferences on the information provided: different information resulted in significantly different choices.     

Ricardian equivalence and fiscal distortions in the Dominican Republic

This paper tests the Ricardian equivalence hypothesis in the context of the Dominican Republic (DR). The results rejected the Ricardian theorem but a weaker version is shown to have significant implications for the DR. If the government borrows to increase spending, private consumption is crowded out and the economy will suffer in the long run. The outcome is worst if the government borrows to deliver a tax cut. In particular, for every RD$ 1.00 of additional debt incurred to finance government primary spending, private consumption and gross domestic product (GDP) fall by a meaningful RD$ 2.15 and RD$ 1.15 respectively. If the debt is used to finance the tax cut, the fall is RD$ 2.15 in both consumption and output. Interestingly, if the government uses taxes to cover a budget deficit, the effect is neutral and consistent with Ricardian equivalence. The paper argues that fiscal distortions are in part responsible for these multipliers. Distortions are estimated to be 21 % coming from different sources including taxes evasion and fiscal drainage. These findings suggest that the DR could benefit from either reducing the level of fiscal distortions or the size and scope of the Dominican government. If, however, the government continues to pursue an active fiscal role under the current environment, it will generate an unnecessary burden to consumption and economic growth.     

Property rights as a complex adaptive system: how entrepreneurship transforms intellectual property structures

This article aims to provide some elements of an evolutionary theory of property rights. It applies a systems-based capital-theoretic perspective to explain the formation and transformation of property rights structures. The approach emphasizes how entrepreneurs create capital combinations by connecting capital goods—defined widely to include property rights, such as patents—in their production plans. Their actions change complementarity relations between property rights as used in production. We treat the property rights structure as a complex adaptive system that exhibits increasing structural complexity as it evolves. Entrepreneurs discover gaps in the property rights system. As they organize production to exploit profit opportunities, entrepreneurs regroup existing intellectual property rights (IPR) into new modules, such as patent pools, that encapsulate more complex combinations of basic building blocks of intellectual property. A patent pool constitutes an interpolation of a new meso level within the macro IPR structure. We apply our framework to the first of the patent pools for digital video compression technology used in digital television and DVDs.     

The best-shot all-pay (group) auction with complete information

We analyze an all-pay group contest in which individual members’ efforts are aggregated via the best-shot technology and the prize is a public good for the winning group. The interplay of within-group free-riding and across-group competition allows for a wide variety of equilibria, according to how well groups overcome internal free-riding. In contrast with the existing literature, we derive equilibria of a symmetric model in which multiple agents per group are active. Our findings differ qualitatively from those of the individualistic all-pay auction: rents are not necessarily dissipated in equilibrium, total expected efforts vary across equilibria, and participation is expected to be greater. Moreover, equilibria with greater symmetry of behavior within a group are shown to have more “wasted” effort but also greater payoffs as overall efforts are lower. In contrast to standard economic intuition, free-riding can be beneficial for players as it reduces competition among groups. Examples of asymmetric group contests are also studied.     

Economic evaluation of BST-CarGel as an adjunct to microfracture vs microfracture alone in knee cartilage surgery

Objectives:

Knee cartilage damage is a common cause of referral for orthopedic surgery. Treatment aims to reduce pain and symptoms by repairing cartilage. Microfracture, the current standard of care, yields good short-term clinical outcomes; however, treatment might fail after 2–3 years. A Chitosan-Beta glycerolphosphate-based medical device (BST-CarGel) is used as an adjunct to microfracture and demonstrates improvements in quantity and quality of repaired tissue, potentially reducing the risk of treatment failure. This study aimed to establish the economic value of BST-CarGel vs microfracture alone in knee cartilage repair from the societal perspective, using Germany as the reference market.

Methods:

A decision tree with a 20-year time-horizon was constructed, in which undesirable clinical events were inferred following initial surgery. These events consisted of pain management, surgery, and total knee replacement. Clinical outcomes were taken from the pivotal clinical trial, supplemented by other literature. Data and assumptions were validated by a Delphi panel. All relevant resource use and costs for procedures and events were considered.

Results:

In a group of patients with all lesion sizes, the model inferred that BST-CarGel yields a positive return on investment at year 4 (with 20-year cumulative cost savings of €6448). Reducing the incremental risk of treatment failure gap between the device and microfracture by 25–50% does not alter this conclusion. Cost savings are greatest for patients with large lesions; results for patients with small lesions are more modest.

Limitations:

Clinical evidence for microfracture and other interventions varies in quality. Comparative long-term data are lacking. The comparison is limited to microfracture and looks only at costs without considering quality-of-life.

Conclusion:

BST-CarGel potentially represents a cost-saving alternative for patients with knee cartilage injury by reducing the risk of clinical events through regeneration of chondral tissue with hyaline characteristics. Since the burden of this condition is high, both to the patient and society, an effective and economically viable alternative is of importance.     

Comparing post-operative resource consumption following transcatheter aortic valve implantation (TAVI) and conventional aortic valve replacement in the UK

Objective:

To define the in-hospital and 6-month post-discharge resource use, following Transcatheter Aortic Valve Implantation (TAVI) and conventional Aortic Valve Replacement (AVR) surgery within a single UK hospital.

Methods:

A local service evaluation of patients undergoing TAVI or AVR between January 2011 and May 2012 captured data until 6-months post-procedure, collected from hospital records and via a General Practitioner questionnaire. The main end-points were mortality, time in ITU/HDU, hospital length of stay (LoS), discharge destination, re-admission, and post-discharge primary/secondary care resource use. Sub-group analyses were performed for AVR patients aged ≥80 (AVR?≥?80) and with EuroSCORE of ≥10 (AVR ES?≥?10) to allow more direct comparison with ‘TAVI type’ patients.

Results:

Results are given as means (standard deviation) for TAVI (n?=?51), AVR (n?=?188), AVR?≥?80 (n?=?48), and AVR ES?≥?10 (n?=?47), respectively, unless otherwise stated. Age in years was 83.0 (8.1), 71.2 (13.1), 84.1 (2.7), 79.4 (7.1); EuroSCORE was 24.7 (11.9), 8.1 (6.4), 12.0 (6.0), and 16.5 (6.6); post-operative LoS (days) was 11.5 (11.2), 10.9 (10.8), 14.3 (16.7), and 15.2 (17.7). For discharged patients, 0%, 7%, 13%, and 9% had unplanned cardiac-related re-admissions within 30-days of discharge. Time to first readmission was 74.6 (34.0), 35.0 (34.2), 20.8 (9.7), and 22.6 (14.3) days.

Limitations:

This was a single-center retrospective evaluation, not prospectively powered to confirm differences in outcomes.

Conclusions:

Despite TAVI being performed in an older, higher risk population, LoS was similar to AVR. Most strikingly there were no cardiac-related re-admissions within 30-days for TAVI and time to first re-admission was significantly longer. This evaluation suggests that TAVI is clinically appropriate and provides economic advantages in both the hospital and post-discharge setting in this high risk group. Many patients undergoing TAVI are considered unfit for surgery and, hence, TAVI offers a treatment that delivers similar results to traditional AVR without the high risk associated with surgery.