Measurement of patient-reported outcomes. 1: The search for the Holy Grail

Abstract

Patient-reported outcome measures (PROMs) are used to collect information directly from patients. They may cover several different types of outcomes ranging from symptoms, functioning, utility, satisfaction, through to quality-of-life (QoL). They generally consist of self-completed questionnaires that can be administered by means of hard copies or in a range of electronic formats. PROMs vary considerably in terms of the constructs they assess, the care with which they are developed, and their scientific quality. However, none of the PROMs available approach the quality of measurement achieved by measures/instruments used in physics. PROs are examples of latent variables. These are not directly observable, but can be inferred from, for example, responses to a questionnaire. The only measure of a latent variable that approaches the quality of measurement achieved by the physical sciences is the Lexile Framework for Reading. This framework is based on a construct theory that grew out of an analysis of several available reading measures. A specification equation was generated that was able to link the construct theory to scores obtained with the Lexile measure. A fundamental requirement of this quality of measurement is that the data collected with the model fit Rasch Measurement Theory (RMT). It is argued that PROM developers should aspire to match this level of measurement sophistication if their instruments are to provide valid insights into the impacts of disease and its treatment.     

Non-cooperative exploitation of multi-cohort fisheries—The role of gear selectivity in the North-East Arctic cod fishery

North-East Arctic cod is shared by Russia and Norway. Taking its multi-cohort structure into account, how would optimal management look like? How would non-cooperative exploitation limit the obtainable profits? To which extent could the strategic situation explain today’s over-harvesting? Simulation of a detailed bio-economic model reveals that the mesh size should be significantly increased, resulting not only in a doubling of economic gains, but also in a biologically healthier age-structure of the stock. The Nash equilibrium is close to the current regime. Even when effort is fixed to its optimal level, the non-cooperative choice of gear selectivity leads to a large dissipation of rents.     

Symposium on Social Capital: Introduction

This symposium contains three papers that discuss aspects of social capital. Social capital has become a major focus of research in many social sciences. Its increased prominence in economics reflects a general increase in interest in questions that have traditionally been deemed sociological. Regardless of one's opinion of social capital per se , this broadening of questions addressed within economics has been very salutary.     

When it Rains,it Pours: Estimating the Spatial Spillover Effect of Rainfall

Environmental and Resource Economics - A large fraction of the world’s poor rely on rain-fed agriculture, which makes them vulnerable to changes in rainfall patterns. In this paper, we...     

Common pool resources and contextual factors: Evolution of a fishermen's cooperative in Calcutta

The CPR school has successfully rebutted Hardin's pessimistic Tragedy of the Commons model. However, in recent years, critics have focussed on the inward orientation and lack of contextual analysis characterising the writings of the CPR school.Oakerson [A Model for the analysis of common property problems. Working Paper R86-13. Workshop in Political Theory and Policy Analysis, Indiana University, 1986] and Ostrom [Governing the Commons. Cambridge, Cambridge University Press, 1990] have detailed the list of variables that have to be studied to understand the mechanics of collective action. However, these factors are internal to the community. Recent critics' point out that the actions of individual agents are also influenced by the alternatives embedded outside the system. These variables are collectively labelled contextual factors.In our paper, we have analysed the case of a fishermen's cooperative in the Calcutta Metropolitan District to show how the historic and economic context shapes targets of resource users and affects the feasibility of alternative courses to achieve the target by determining opportunity and transaction costs of actions. This indicates the importance of contextual factors in explaining the formation and evolution of the resource regime.     

Exchange rates dynamics revisited: a panel data test of the fractional integration order

We test the possibility that exchange rates from nine developed countries have a unit root against the alternate possibility that they are fractionally integrated. Theoretically, exchange rates are only expected to follow a random walk under restrictive assumptions. However, most traditional unit root tests cannot reject a unit root in exchange rates, and time series tests that allow for fractional integration have given inconclusive results. To increase the power of the test of the integration order we develop two panel data tests of the fractional integration order. Monte Carlo simulations show that these tests are correctly sized and have relatively high power compared to other similar tests. Moreover, our empirical results show that we can reject a unit root in exchange rates with a high probability, but the integration order is close to one. This indicates that exchange rates are mean-reverting, although the reversion is slow, resulting in long swings.     

Discontinuous innovation capability accumulation in latecomer natural resource-processing firms

Most of the studies that describe the building of innovation capability in emerging and developing economies have focused on the ways in which latecomer firms develop continuously towards advanced capability levels along existing technological trajectories, particularly for the assembled products industries, especially in Asia. A slightly different approach is adopted herein by focusing on pathways of discontinuous capability building of firms in natural resource-processing industries. By drawing on evidence from a variety of case studies taken from 13 forestry, pulp, and paper firms in Brazil in the period 1950-2007, it was found that: (1) in contrast with the majority of case studies reported in the literature, the pathways followed by firms in their accumulation of innovation capability involved a qualitative departure from the established technological trajectory at an early stage in the development of their capability; (2) the pathways of firms along the new technological trajectories were nevertheless characterised by a high degree of variability (from intermediate to world leading innovators) in terms of the levels and speeds of the accumulation of innovation capability; (3) firms that have attained progressively higher levels of innovative performance have more rapidly developed a combination of internal and external research-based arrangements in order to undertake increasingly complex, but firm-centred innovation efforts. This paper sheds some light on some of the discussions that relate to the role of natural resources in the patterns of industrial progress and growth in those countries endowed with particular natural resource-based industries. It also provides a methodological contribution to the study of the long-term innovation strategies that make use of the dynamics of capability building, especially within natural resource-processing industries.     

A comparison of citizen and “expert” preferences using an attribute-based approach to choice

This paper explores whether expert judgements can be taken as a proxy for citizen preferences for determining investment strategies for public goods. As an illustration, we focus on the provision of Public Rights Of Way (PROW) by Local Government Authorities in England. These provide rights of passage over property to those other than the owners, and little information is available on the welfare effects of changes in the provision and use of PROW. Given limited funds, reliance on expert judgement could be a cost effective alternative for decision-making compared with stated preference surveys of citizens. Two methods are compared. The Analytic Hierarchy Process (AHP) is used to elicit expert judgement to proxy citizen preferences for different attributes of PROW. The Choice Experiment (CE) technique is then used to derive preferences directly through personal interviews with citizens. Overall it was found that judicious use of AHP by experts can, in this instance, be used to represent citizen views. However, this result may not be easily generalisable to other settings.     

Sensitivities for Bermudan options by regression methods

In this article, we propose several pathwise and finite difference-based methods for calculating sensitivities of Bermudan options using regression methods and Monte Carlo simulation. These methods rely on conditional probabilistic representations that allow, in combination with a regression approach, for efficient simultaneous computation of sensitivities at many initial positions. Assuming that the price of a Bermudan option can be evaluated sufficiently accurate, we develop a method for constructing deltas based on least squares. We finally propose a testing procedure for assessing the performance of the developed methods and give a numerical illustration.