Measuring the impact of arthritis on worker productivity : perspectives, methodologic issues and contextual factors

Leading up to the Outcome Measures in Rheumatology (OMERACT) 10 meeting, the goal of the Worker Productivity Special Interest Group (WP-SIG) was to make progress on 3 key issues that relate to the application and interpretation of worker productivity outcomes in arthritis: (1) to review existing conceptual frameworks to help consolidate our intended target and scope of measurement; (2) to examine the methodologic issues associated with our goal of combining multiple indicators of worker productivity loss (e.g., absenteeism <—> presenteeism) into a single comprehensive outcome; and (3) to examine the relevant contextual factors of work and potential implications for the interpretation of scores derived from existing outcome measures. Progress was made on all 3 issues at OMERACT 10. We identified 3 theoretical frameworks that offered unique but converging perspectives on worker productivity loss and/or work disability to provide guidance with classification, selection, and future recommendation of outcomes. Several measurement and analytic approaches to combine absenteeism and presenteeism outcomes were proposed, and the need for further validation of such approaches was also recognized. Finally, participants at the WP-SIG were engaged to brainstorm and provide preliminary endorsements to support key contextual factors of worker productivity through an anonymous “dot voting” exercise. A total of 24 specific factors were identified, with 16 receiving ≥ 1 vote among members, reflecting highly diverse views on specific factors that were considered most important. Moving forward, further progress on these issues remains a priority to help inform the best application of worker productivity outcomes in arthritis research.

Investigation of population heterogeneity of diet use among middle-aged Australians

The purpose of the study was to determine patterns of diet use among middle-aged Australian men and women and the relationships between these different usage patterns and demographic characteristics, health status and health habits. A cross-sectional mail survey was conducted among a random sample of 2975 people aged 40–71 years in Victoria, Australia. A total of 1031 usable questionnaires were obtained which included information about the use of diets (e.g. low-fat and low-salt) during the past 3 months along with demographic information, health status and health habits. Based on the responses about the use of thirteen diets for both sexes, latent class analysis was employed to identify the optimal number of use of diets and the assignment of participants to particular groups. Three types of diet uses were identified and provisionally named: diet use, selected diet use and non-diet use. This classification was associated with demographics, health status and health habits, and these associations differed between men and women. The findings suggest that nutrition education programmes should be tailored to the different needs of the diet use groups.

Firm heterogeneity and calendar anomalies

While the calendar anomalies and financial market relationship is one of the oldest relationships in financial economics, we treat this relationship differently by addressing two unknown issues: (a) Do calendar anomalies have a heterogeneous effect on firm returns and firm volatility depending on the sectoral location of firms? and (b) Do calendar anomalies affect firm returns and firm volatility differently depending on firm size? Unlike the assumption in this literature that firms are homogeneous, we show that they are in fact heterogeneous. Using 560 firms listed on the New York Stock Exchange (NYSE) over the period 5 January 2000 to 31 December 2008, we find fresh results, previously undocumented in this literature. We find evidence of calendar anomalies affecting returns and return volatility of firms differently depending on their sectoral locations and size.

Identification of surface heterogeneity effects in cyclic voltammograms derived from analysis of an individually addressable gold array electrode

Voltammetric behavior at gold electrodes in aqueous media is known to be strongly dependent on electrode polishing and history. In this study, an electrode array consisting of 100 nominally identical and individually addressable gold disks electrodes, each with a radius of 127 µm, has been fabricated. The ability to analyze both individual electrode and total array performance enables microscopic aspects of the overall voltammetric response arising from variable levels of inhomogeneity in each electrode to be identified. The array configuration was initially employed with the reversible and hence relatively surface insensitive [Ru(NH₃)₆]^3+/2+ reaction and then with the more highly surface sensitive quasi-reversible [Fe(CN)₆]^3−/4− process. In both these cases, the reactants and products are solution soluble and, at a scan rate of 50 mV s⁻¹, each electrode in the array is assumed to behave independently, since no evidence of overlapping of the diffusion layers was detected. As would be expected, the variability of the individual electrodesʼ responses was significantly larger than found for the summed electrode behavior. In the case of cytochrome c voltammetry at a 4,4′-dipyridyl disulfide modified electrode, a far greater dependence on electrode history and electrode heterogeneity was detected. In this case, voltammograms derived from individual electrodes in the gold array electrode exhibit shape variations ranging from peak to sigmoidal. However, again the total response was always found to be well-defined. This voltammetry is consistent with a microscopic model of heterogeneity where some parts of each chemically modified electrode surface are electroactive while other parts are less active. The findings are consistent with the common existence of electrode heterogeneity in cyclic voltammetric responses at gold electrodes, that are normally difficult to detect, but fundamentally important, as electrode nonuniformity can give rise to subtle forms of kinetic and other forms of dispersion.

Investor heterogeneity and the cross-sectional stock returns in China

We examine the relationship between divergence of opinion and the cross-sectional stock returns in Chinese A share market where short-selling of stocks is prohibited by law. Using a proxy for divergence of opinion among the entire investor base, we document a positive relationship between divergent beliefs and future stock returns. This is in sharp contrast to Miller's (1977) prediction of a negative relationship between the two. The result is likely to be driven by the dominance of individual investors and their speculative trading behaviors in China. Miller's prediction is confirmed when divergence of opinion is measured using data on mutual fund holdings. Our results are robust to a number of common return predictors. We also find a significantly negative relationship between the fraction of tradable shares in listed Chinese companies and future stock returns. Increase in the fraction of tradable shares tends to reduce the predictability of stock returns using divergence of opinion.

A mixed blessing of lifespan heterogeneity

Human mortality data reveal that life expectancy in industrialized countries has been converging to a common value. Yet, significant variations in the distributions of adult life-table ages at death among some developed countries have also been observed. This paper, largely motivated by Japan’s mortality data, presents a general equilibrium, overlapping-generations model that assesses the welfare effects of the mean-preserving declines in the variance of the distribution of adult ages at death. Our quantitative exercise reveals that for a given value of the economy-wide life expectancy, the individual welfare effects due to switching from high to low-variance steady states are length of life-dependent, quite sensitive to the average economy-wide retirement age, and strongly influenced by associated changes in the labor supply, factor prices, and lifetime earnings.