Is There a Curse of Dimensionality for Contraction Fixed Points in the Worst Case?

This paper analyzes the complexity of the contraction fixed point problem: compute an ε‐approximation to the fixed point V*Γ(V*) of a contraction mapping Γ that maps a Banach space B_d of continuous functions of d variables into itself. We focus on quasi linear contractions where Γ is a nonlinear functional of a finite number of conditional expectation operators. This class includes contractive Fredholm integral equations that arise in asset pricing applications and the contractive Bellman equation from dynamic programming. In the absence of further restrictions on the domain of Γ, the quasi linear fixed point problem is subject to the curse of dimensionality, i.e., in the worst case the minimal number of function evaluations and arithmetic operations required to compute an ε‐approximation to a fixed point V*∈B_d increases exponentially in d. We show that the curse of dimensionality disappears if the domain of Γ has additional special structure. We identify a particular type of special structure for which the problem is strongly tractable even in the worst case, i.e., the number of function evaluations and arithmetic operations needed to compute an ε‐approximation of V* is bounded by Cε^−p where C and p are constants independent of d. We present examples of economic problems that have this type of special structure including a class of rational expectations asset pricing problems for which the optimal exponent p1 is nearly achieved.     

Identification of Standard Auction Models

This paper presents new identification results for models of first–price, second–price, ascending (English), and descending (Dutch) auctions. We consider a general specification of the latent demand and information structure, nesting both private values and common values models, and allowing correlated types as well as ex ante asymmetry. We address identification of a series of nested models and derive testable restrictions enabling discrimination between models on the basis of observed data. The simplest model—symmetric independent private values—is nonparametrically identified even if only the transaction price from each auction is observed. For richer models, identification and testable restrictions may be obtained when additional information of one or more of the following types is available: (i) the identity of the winning bidder or other bidders; (ii) one or more bids in addition to the transaction price; (iii) exogenous variation in the number of bidders; (iv) bidder–specific covariates. While many private values (PV) models are nonparametrically identified and testable with commonly available data, identification of common values (CV) models requires stringent assumptions. Nonetheless, the PV model can be tested against the CV alternative, even when neither model is identified.     

Discrete–Time Approximations of the Holmström–Milgrom Brownian–Motion Model of Intertemporal Incentive Provision

This paper studies the relation between discrete–time and continuous–time principal–agent models. We derive the continuous–time model as a limit of discrete–time models with ever shorter periods and show that optimal incentive schemes in the discrete–time models approximate the optimal incentive scheme in the continuous model, which is linear in accounts. Under the additional assumption that the principal observes only cumulative total profits at the end and the agent can destroy profits unnoticed, an incentive scheme that is linear in total profits is shown to be approximately optimal in the discrete–time model when the length of the period is small.     

Relationships between Sales Management Control, Territory Design, Salesforce Performance and Sales Organization Effectiveness

This research evaluates determinants of sales organization effectiveness in a sample of British companies, and contributes to an important new research stream by following recent empirical studies in the USA and Australia. We discuss a model of sales organization effectiveness determined by salesforce outcome performance and behavioural performance, as well as by the use of a behaviour-based control approach. Sales territory design is also considered as a particularly important managerial variable, which has received little analytical attention in the traditional literature, but which appears to be an important influence on the effectiveness of the sales operation. Our exploratory path analytical model suggests that sales territory design has a large effect on sales organization effectiveness both directly, and indirectly through its relationship with salesforce behavioural performance. These findings are somewhat different to those in similar studies in other countries, and suggest some important implications for managers as well as for researchers in this field.     

Psychosocial versus biomedical risk factors in Kevorkian's first forty-seven physician-assisted deaths

This article examines biomedical and psychosocial data on the first forty-seven cases of physician-assisted suicide (PAS) of Kevorkian as collected by means of both a physical autopsy and a preliminary psychological autopsy. The following patterns emerge: 1) The physical condition of these PAS patients was not typical of the conditions that lead to death in the United States. 2) Consistent with the above findings, our pilot data indicate that only 31.1 percent of these patients were terminal. While 73.9 percent were described as reporting pain, only 42.6 percent were revealed at autopsy to have a specific anatomical basis for their pain. However 36 percent were described as depressed, 66 percent as having some disability, and perhaps of key importance, 90 percent expressed a fear of dependency. Most important, our pilot data suggest the possibility of large gender differences, since 3) 68.1 percent of these forty-seven PAS's are women and only 31.9 percent are men. This represents the reverse of the gender pattern for completed suicides in the United States in 1995, resembling instead the approximate pattern for unsuccessful suicide attempts. 4) Approximately 75 percent of both men and women in the above sample were described as reporting pain. Men were almost twice as likely to have had an anatomical basis for the pain and three times as likely to be terminal. Our pilot data indicate PAS women are more likely to be described as depressed and twice as likely to have had a history of previous unsuccessful suicide attempts. 5) Kevorkian's patients were older than the typical unaided suicides in America. Reported pain decreases with age as does depression; however anatomical basis for pain increases slightly with age, and no age effect emerges for terminality. 6) Approximately two-thirds of those physician-assisted suicides were at middle SES levels. History of disability was the biggest risk factor for the low SES patients and fear of dependency for the high SES patients.     

The development of the physicians' end-of-life care attitude scale

The Physicians' End-of-Life Care Attitude Scale (PEAS) was developed as an outcome measure for palliative care education. PEAS assesses the willingness of medical trainees to care for dying patients. Sixty-four Likert-type questions were created on the basis of discussions with focus groups of medical trainees, then administered to sixty-two medical students and residents. Total PEAS scores as well as personal preparation and professional role subscales (where higher scores indicated greater concern) possessed excellent internal consistency and reliability. In addition, there were substantial correlations between PEAS scores and the CA-Dying scale, a measurement of laypersons' fears about interacting with dying persons. Thus, PEAS adequately assesses the unique communication concerns of physicians in training regarding working with dying persons and their families. Correlations between PEAS scores and age were negative, while those who had experienced the death of a loved one had higher PEAS scores than those who did not. This suggests that for some persons, life experiences may lessen difficulties in dealing with dying persons, while for others, personal losses may exacerbate such concerns. The utility of PEAS in evaluating the efficacy of palliative care education as well as its potential to measure medical trainee's willingness to care for the terminally ill is discussed.     

Paving the road to hell: why change programs ultimately fail

A successful change program must have clearly delineated and honestly defined goals. Change requires conviction, money, and effort and the willingness to invest all three. Change programs fail when any of these requirements are lacking. Many health care executives have the conviction, but are unwilling to spend the money or expend the effort. Some lack conviction, despite having money; the effort is merely spinning wheels with no forward motion. Often all three are lacking, despite an outward appearance to the contrary--the result of management delusions. Employees are quick to see through misleading and insincere schemes. It is much easier to foster trust from the outset than to rebuild it after it has been violated.     

Intensity of Interaction in Supply of Business Advice and Client Impact: A Comparison of Consultancy,Business Associations and Government Support Initiatives for SMEs

This paper assesses the supply of business advice using new empirical evidence from a large-scale survey of SMEs. The chief focus of the paper is on a comparison of suppliers that operate in different environments of regulation, contract and reputation. The paper argues that interaction intensity varies with the level of information asymmetry of these different environments, between different types of service supplier and their clients. Interaction intensity between suppliers also varies as a result of the level of trust they enjoy: for example, the low trust enjoyed by consultants appears to encourage higher intensity of interaction which improves the tailoring of the service to the client's needs and enhances impact. The paper assesses interaction intensity using the existence of site visits and/or a written brief/contract as indicators. Although these measures have limitations, the paper demonstrates clear and significant differences between suppliers in terms of interaction intensity, use of contracts and impact in three broad categories: private-sector consultancy (low trust, high intensity, high impact), business associations (high trust, low intensity, moderate impact) and government support agencies (moderate trust, moderate to high intensity, moderate or low impact). Multivariate estimation methods demonstrate that significant differences in interaction intensity, use of contracts and impact by client type are much less important than differences in supplier type. This indicates that suppliers generally develop more into niche service fields or groups of services rather than niches related to types of firm.