Hidden regret in insurance markets: adverse and advantageous selection

We examine insurance markets with two types of customers: those who regret suboptimal decisions and those who don.t. In this setting, we characterize the equilibria under hidden information about the type of customers and hidden action. We show that both pooling and separating equilibria can exist. Furthermore, there exist separating equilibria that predict a positive correlation between the amount of insurance coverage and risk type, as in the standard economic models of adverse selection, but there also exist separating equilibria that predict a negative correlation between the amount of insurance coverage and risk type, i.e. advantageous selection. Since optimal choice of regretful customers depends on foregone alternatives, any equilibrium includes a contract which is o¤ered but not purchased

Spanning Trees on Hypercubic Lattices and Non-orientable Surfaces

We consider the problem of enumerating spanning trees on lattices. Closed-form expressions are obtained for the spanning tree generating function for a hypercubic lattice of size N_1 x N_2 x...x N_d in d dimensions under free, periodic, and a combination of free and periodic boundary conditions. Results are also obtained for a simple quartic net embedded on two non-orientable surfaces, a Moebius strip and the Klein bottle. Our results are based on the use of a formula expressing the spanning tree generating function in terms of the eigenvalues of an associated tree matrix. An elementary derivation of this formula is given.Comment: latex, 9 pages, no figures, to appear in Lett. Appl. Mat

Perspectives of staff nurses of the reasons for and the nature of patient-initiated call lights: an exploratory survey study in four USA hospitals

<p>Abstract</p> <p>Background</p> <p>Little research has been done on patient call light use and staff response time, which were found to be associated with inpatient falls and satisfaction. Nurses' perspectives may moderate or mediate the aforementioned relationships. This exploratory study intended to understand staff's perspectives about call lights, staff responsiveness, and the reasons for and the nature of call light use. It also explored differences among hospitals and identified significant predictors of the nature of call light use.</p> <p>Methods</p> <p>This cross-sectional, multihospital survey study was conducted from September 2008 to January 2009 in four hospitals located in the Midwestern region of the United States. A brief survey was used. All 2309 licensed and unlicensed nursing staff members who provide direct patient care in 27 adult care units were invited to participate. A total of 808 completed surveys were retrieved for an overall response rate of 35%. The SPSS 16.0 Window version was used. Descriptive and binary logistic regression analyses were conducted.</p> <p>Results</p> <p>The primary reasons for patient-initiated calls were for toileting assistance, pain medication, and intravenous problems. Toileting assistance was the leading reason. Each staff responded to 6 to 7 calls per hour and a call was answered within 4 minutes (estimated). 49% of staff perceived that patient-initiated calls mattered to patient safety. 77% agreed that that these calls were meaningful. 52% thought that these calls required the attention of nursing staff. 53% thought that answering calls prevented them from doing the critical aspects of their role. Staff's perceptions about the nature of calls varied across hospitals. Junior staff tended to overlook the importance of answering calls. A nurse participant tended to perceive calls as more likely requiring nursing staff's attention than a nurse aide participant.</p> <p>Conclusions</p> <p>If answering calls was a high priority among nursing tasks, staff would perceive calls as being important, requiring nursing staff's attention, and being meaningful. Therefore, answering calls should not be perceived as preventing staff from doing the critical aspects of their role. Additional efforts are necessary to reach the ideal or even a reasonable level of patient safety-first practice in current hospital environments.</p

The contribution of staff call light response time to fall and injurious fall rates: an exploratory study in four US hospitals using archived hospital data

Abstract Background Fall prevention programs for hospitalized patients have had limited success, and the effect of programs on decreasing total falls and fall-related injuries is still inconclusive. This exploratory multi-hospital study examined the unique contribution of call light response time to predicting total fall rates and injurious fall rates in inpatient acute care settings. The conceptual model was based on Donabedian's framework of structure, process, and health-care outcomes. The covariates included the hospital, unit type, total nursing hours per patient-day (HPPDs), percentage of the total nursing HPPDs supplied by registered nurses, percentage of patients aged 65 years or older, average case mix index, percentage of patients with altered mental status, percentage of patients with hearing problems, and call light use rate per patient-day. Methods We analyzed data from 28 units from 4 Michigan hospitals, using archived data and chart reviews from January 2004 to May 2009. The patient care unit-month, defined as data aggregated by month for each patient care unit, was the unit of analysis (N = 1063). Hierarchical multiple regression analyses were used. Results Faster call light response time was associated with lower total fall and injurious fall rates. Units with a higher call light use rate had lower total fall and injurious fall rates. A higher percentage of productive nursing hours provided by registered nurses was associated with lower total fall and injurious fall rates. A higher percentage of patients with altered mental status was associated with a higher total fall rate but not a higher injurious fall rate. Units with a higher percentage of patients aged 65 years or older had lower injurious fall rates. Conclusions Faster call light response time appeared to contribute to lower total fall and injurious fall rates, after controlling for the covariates. For practical relevance, hospital and nursing executives should consider strategizing fall and injurious fall prevention efforts by aiming for a decrease in staff response time to call lights. Monitoring call light response time on a regular basis is recommended and could be incorporated into evidence-based practice guidelines for fall prevention.http://deepblue.lib.umich.edu/bitstream/2027.42/112579/1/12913_2011_Article_2004.pd

Modeling and Evaluating of Business Revenue Models under Different Product Life Cycles Using System Dynamics Simulation

Business revenue modelling is one of the important aspects of enterprise planning to create values for enterprises. In this study, we construct a system dynamics simulation model to evaluate various business revenue models applied to e-platforms. Machining tools industry is investigated as a case study. Products with different life cycles are examined as applying different business models. Computational experiments are conducted and results are discussed. Specific research issues/contributions of the study include: 1. To propose four effective business revenue models in such an industry. 2. To evaluate the proposed business revenue models as well as their advantages/disadvantages by a system dynamics simulation. 3. To address managerial implications of these business revenue models to the industry. As a conclusion to our research, we show that: (i) Firms with products under growth or mature stage of life cycle adopt/switch appropriate business revenue models conforming to their requirements in different stages and result in high performance outcomes than those remaining in a single business revenue model. (ii) Business revenue models represented by causal loops of system dynamics and examined by system simulation can capture not only steady states but transient states of business activities. By taking advantages of the proposed approach, managers can thus efficiently make right decisions for reducing time and cost

Hidden Regret and Advantageous Selection in Insurance Markets

We examine insurance markets in which there are two types of customers: those who regret suboptimal decisions and those who don\u27t. In this setting, we characterize the equilibria under hidden information about the type of customers and hidden action. We show that both pooling and separating equilibria can exist. Furthermore, there exist separating equilibria that predict a positive correlation between the amount of insurance coverage and risk type, as in the standard economic models of adverse selection, but there also exist separating equilibria that predict a negative correlation between the amount of insurance coverage and risk type, i.e. advantageous selection. Since optimal choice of regretful customers depends on foregone alternatives, any equilibrium includes a contract which is not purchased

Exposing errors related to weak memory in GPU applications

© 2016 ACM.We present the systematic design of a testing environment that uses stressing and fuzzing to reveal errors in GPU applications that arise due to weak memory effects. We evaluate our approach on seven GPUS spanning three NVIDIA architectures, across ten CUDA applications that use fine-grained concurrency. Our results show that applications that rarely or never exhibit errors related to weak memory when executed natively can readily exhibit these errors when executed in our testing environment. Our testing environment also provides a means to help identify the root causes of such errors, and automatically suggests how to insert fences that harden an application against weak memory bugs. To understand the cost of GPU fences, we benchmark applications with fences provided by the hardening strategy as well as a more conservative, sound fencing strategy

Theory of impedance networks: The two-point impedance and LC resonances

We present a formulation of the determination of the impedance between any two nodes in an impedance network. An impedance network is described by its Laplacian matrix L which has generally complex matrix elements. We show that by solving the equation L u_a = lambda_a u_a^* with orthonormal vectors u_a, the effective impedance between nodes p and q of the network is Z = Sum_a [u_{a,p} - u_{a,q}]^2/lambda_a where the summation is over all lambda_a not identically equal to zero and u_{a,p} is the p-th component of u_a. For networks consisting of inductances (L) and capacitances (C), the formulation leads to the occurrence of resonances at frequencies associated with the vanishing of lambda_a. This curious result suggests the possibility of practical applications to resonant circuits. Our formulation is illustrated by explicit examples.Comment: 21 pages, 3 figures; v4: typesetting corrected; v5: Eq. (63) correcte