Estimating rating transition probabilites with missing data

In this article we provide a rigorous treatment of one of the central statistical issues of credit risk management. GivenK-1 rating categories, the rating of a corporate bond over a certain horizon may either stay the same or change to one of the remainingK-2 categories; in addition, it is usually the case that the rating of some bonds is withdrawn during the time interval considered in the analysis. When estimating transition probabilities, we have thus to consider aK-th category, called withdrawal, which contains (partially) missing data. We show how maximum likelihood estimation can be performed in this setup; whereas in discrete time our solution gives rigorous support to a solution often used in applications, in continuous time the maximum likelihood estimator of the transition matrix computed by means of the EM algorithm represents a significant improvement over existing methods.     

Monitoring the coefficient of variation using a variable sample size and sampling interval control chart

This article proposes a CV chart by using the variable sample size and sampling interval (VSSI) feature to improve the performance of the basic CV chart, for detecting small and moderate shifts in the CV. The proposed VSSI CV chart is designed by allowing the sample size and the sampling interval to vary. The VSSI CV chart's statistical performance is measured by using the average time to signal (ATS) and expected average time to signal (EATS) criteria and is compared with that of existing CV charts. The Markov chain approach is employed in the design of the chart.     

Ridge regression: A multivariate analysis of criminal activity

The objective of the paper is to apply the statistical procedure of ridge regression to a multivariate model of criminal activity. The explanatory variables are of an economic, apprehension, and seasonal nature. The Time Shared Reactive On Line Laboratory (TROLL) computer package was used in estimating all regression coefficients and other pertinent statistics. The economic variables, which included per capita personal income, hours worked, and plant closing dummy variable, were found to be statistically related to criminal activity. In addition, police expenditures as well as the three seasonal dummy variables were statistically associated with the dependent variable. A comparison is made between the results obtained from the ordinary least squares procedure and the ridge regression approach.     

Invisible or Mainstream? Disability in Surveys and Censuses in Low- and Middle-Income Countries

Social Indicators Research - This paper examines to what extent household surveys and censuses in low- and middle-income countries include disability questions and the types of questions under use....     

Integrations,identity and conflicts: A cross-border perspective on residential relocation of Hong Kong citizens to Mainland China

This paper aims to test if traditional literature on both internal residential mobility and international migration hold up in explaining the driving forces behind the home-moving behaviours of Hong Kong residents to the Chinese Mainland, under a mixture of economic integrations, past connections along with present structural and identity differences. The multi-dimensionality of this behaviour, in comparison to other forms of residential movements in the literature, is shown as there is no single attribute, albeit all necessary conditions, sufficient enough to encourage such movement on its own. Instead, the cross-border residence is primarily a middle-class, middle-aged phenomenon, due to one’s past connections with Mainland China throughout his/her life course and the possession of financial resources insufficient to afford larger living space in Hong Kong yet enough to benefit from the remarkable living cost advantages on the other side of the border. It provides some directions for studying similar forms of residential mobility in the era of globalization when the functions of national borders have become more obscure than before. Implications from this residential behaviour are then discussed.     

Roadmap to recovery: Reporting on a research taskforce supporting Indigenous responses to COVID‐19 in Australia

In April 2020 a Group of Eight Taskforce was convened, consisting of over 100 researchers, to provide independent, research‐based recommendations to the Commonwealth Government on a “Roadmap to Recovery” from COVID‐19. The report covered issues ranging from pandemic control and relaxation of social distancing measures, to well‐being and special considerations for vulnerable populations. Our work focused on the critical needs of Aboriginal and Torres Strait Islander communities; this paper presents an overview of our recommendations to the Roadmap report. In addressing the global challenges posed by pandemics for citizens around the world, Indigenous people are recognised as highly vulnerable. At the time of writing Australia's First Nations Peoples have been largely spared from COVID‐19 in comparison to other Indigenous populations globally. Our recommendations emphasise self‐determination and equitable needs‐based funding to support Indigenous communities to recover from COVID‐19, addressing persistent overcrowded housing, and a focus on workforce, especially for regional and remote communities. These latter two issues have been highlighted as major issues of risk for Indigenous communities in Australia It remains to be seen how governments across Australia take up these recommendations to support Indigenous peoples' health and healing journey through yet another, potentially catastrophic, health crisis.     

The effect of migration on ages at vital events: A critique of family reconstitution in historical demography

Demographic rates of historical populations have usually been calculated using only data from stayers alone. Can they be extrapolated to the population as a whole? Ruggles has recently pointed out, using both logic and a computer simulation, that stayers experience vital events earlier in life than movers due to migration censorship: those who experience them later in life have often migrated away from the community being studied. We show that stayers do indeed marry and die at younger ages than do movers, using a genealogical database on the American North (1620–1880). These differences are caused, however, both by migration censorship and by genuine differences between the two groups and the places they lived. Therefore changes over time among stayers are not good indicators of changes in the population as a whole because they are affected by changing migration rates. Thus no simple “correction factor” can be extrapolated to estimate the general population; neither stayers (nor movers) constitute a “baseline” or “normal” process: both must be considered together in order to gain an accurate picture of the population as a whole.