Market-Based Credit Ratings

We present a methodology for rating in real-time the creditworthiness of public companies in the U.S. from the prices of traded assets. Our approach uses asset pricing data to impute a term structure of risk neutral survival functions or default probabilities. Firms are then clustered into ratings categories based on their survival functions using a functional clustering algorithm. This allows all public firms whose assets are traded to be directly rated by market participants. For firms whose assets are not traded, we show how they can be indirectly rated by matching them to firms that are traded based on observable characteristics. We also show how the resulting ratings can be used to construct loss distributions for portfolios of bonds. Finally, we compare our ratings to Standard & Poors and find that, over the period 2005 to 2011, our ratings lead theirs for firms that ultimately default.     

Questions of process in participant-generated visual methodologies

There is an increasing literature on visual methodologies in which images are generated by participants as part of the research, as distinct from the analysis of existing images or images taken by the researcher. Although there are growing numbers of publications that present frameworks for analysing images and their meaning, this is an area requiring further deliberation and consolidation. Our contribution is to give serious attention to the processes of image production in participant-generated visual methodologies. We examine methodological and ethical considerations that arise before, during and after image production. Our work is in health research and we focus specifically on two methods: first, a combination of photovoice and photo-elicitation, in particular with young people; and second, drawings as research method. Based on examples using these two methods, we pose questions of process for image production and submit this for interrogation for reasons of methodological, analytical and ethical rigour.     

Sexually transmitted infections in the older woman

Dependent upon sexual behaviour peri- and postmenopausal women are increasingly at risk of sexually transmitted infections, although the overall rates remain low when compared with younger people. Symptoms are often non-specific or absent and may be misinterpreted as being due to the menopause. In addition, both the women and their clinicians may not be aware of their infection risk, thus leading to a delayed or missed diagnosis. Risk assessment and referral for screening of infections should be carried out wherever appropriate.     

A special section for correspondence and controversy

Editor's Note: This update was prepared before devaluation of the Mexican currency impaired Mexico's capacity to import U.S. goods and services, which had been the primary benefit expected from the NAFTA.     

Performance of the weighted least squares apprdach to categorical data analysis

The weighted least squares method of Grizzle, Starmer and Koch is a common and convenient way to analyze categorical data. Tests of significance based on this method are typically performed by calculating a quadratic form which is asymptotically distrib-uted as a chi-square random variable under an appropriate null hy- pothesis.

This paper explores the validity of this distributional approximation for small samples in terms of the accuracy and power associated with this chi-square statistic. We report simulation results from the weighted least squares method applied to balanced factorial experiments, The simulations which constitute the majorpart of this work also provide insight into the relative performance of several response functions.     

Examining the historical and present energy metabolism of a Rust Belt City: Syracuse,NY 1840–2005

Early cities depended on local, solar-based energy resources for their metabolism. Over time, cities have become increasingly dependent on fossil fuels, both directly and indirectly, as they facilitate exploitation of solar resources from much farther away. Alternatives to fossil fuels, typically generated locally, often provide lower surplus energy to society. As cities consider the transition back to solar-based energy resources, it becomes necessary to understand the capability of the solar-based economy to provide e.g. energy (including food) from nearby lands. To do so, we compared the energy metabolism (respiration) of a typical rust-belt city, Syracuse, NY, with the net primary production in the surrounding county (production) over its development (1840–2005). We calculated the ratio of respiration to production (R:P) and examined how this ratio changed during the periods of industrialization, shifts in major fuel types, and deindustrialization. We found that from 1840 to 1950 respiration became increasingly centralized in the urban core; since then it has become more diffused. Urban respiration exceeded production in the county by 9:1 in 1930, and it remains just under 2:1 today. Respiration reached an absolute (67 PJ) and a per capita (339 GJ) maximum in 1970, then fell by 40 % and 20 % respectively, due to deindustrialization and population losses. Conversely, production increased 480 % from its lows in 1930 because of reforestation and improved agricultural yields. What this means is that to achieve a higher P:R ratio requires either increased production of food and fuels in areas surrounding the city, or decreased per capita energy consumption.     

Poster Abstracts

Objectives. To analyse the relation between results of the Aging Males' Symptoms (AMS) questionnaire for aging males, and of quality of life (QOL) questionnaire SF-12 and cardiovascular risk factors.

Methods. 1,927 men aged 55–85 years were interviewed by 56 general practitioners. During the interview the men were asked to fill in the AMS scale and the QOL questionnaire SF-12.

Results. Of 1,927 men 1,806 men filled correctly the AMS questionnaire. The mean SF-12 mental index was respectively 55.9 in men with a total AMS score indicating no impairment, 50.9 mild, 42.8 moderate, and 32.8 severe impairment. The corresponding values for the physical index were 51.2, 46.7, 40.8 and 32.3.

A history of diabetes was associated with an increased risk of reporting moderate/severe impairment: in relation to the total AMS score the odds ratio, (OR), of moderate/severe impairment in comparison with no impairment was 1.6 (95%CI 1.2–2.1). A history of myocardial infarction and hypertension increased the risk (respectively OR 1.4 (95%CI 1.1–18) and 1.7 (95%CI 1.2–2.4)).

Conclusions. This study shows that higher AMS scores are associated with lower SF-12 indices and suggests that elevated values of the AMS score are associated with cardiovascular risk factors or diseases.     

The Distribution of the Kolmogorov–Smirnov,Cramer–von Mises,and Anderson–Darling Test Statistics for Exponential Populations with Estimated Parameters

This article presents a derivation of the distribution of the Kolmogorov–Smirnov, Cramer–von Mises, and Anderson–Darling test statistics in the case of exponential sampling when the parameters are unknown and estimated from sample data for small sample sizes via maximum likelihood.