Estimating Small Area Income Deprivation: An Iterative Proportional Fitting Approach

Small area estimation and in particular the estimation of small area income deprivation has potential value in the development of new or alternative components of multiple deprivation indices. These new approaches enable the development of income distribution threshold based as opposed to benefit count based measures of income deprivation and so enable the alignment of regional and national measures such as the Households Below Average Income with small area measures. This paper briefly reviews a number of approaches to small area estimation before describing in some detail an iterative proportional fitting based spatial microsimulation approach. This approach is then applied to the estimation of small area HBAI rates at the small area level in Wales in 2003-5. The paper discusses the results of this approach, contrasts them with contemporary ‘official’ income deprivation measures for the same areas and describes a range of ways to assess the robustness of the results

Neighbourhoods and oral health:Agent-based modelling of tooth decay

This research used proof of concept agent-based models to test various theoretical mechanisms by which neighbourhoods may influence tooth decay in adults. Theoretical pathways were constructed using existing literature and tested in two study areas in Sheffield, UK. The models found a pathway between shops and sugar consumption had the most influence on adult tooth decay scores, revealing that similar mechanisms influence this outcome in different populations. This highlighted the importance of the interactions between neighbourhood features and individual level variables in influencing outcomes in tooth decay. Further work is required to improve the accuracy and reliability of the models

Exploring ethnic inequalities in health: Evidence from the Health Survey for England, 1998-2011

Issues of social justice and social and spatial inequalities in health have long been researched, yet there is a relative paucity of research on ethnic inequalities in health. Given the increasing ethnic diversity of England's population and the persistence of unjust differences in health this research is timely. We used annual data from the Health Survey for England between 1998 and 2011, combined into a time-series dataset, to examine the influence of socioeconomic and spatial factors on ethnic variations in health and to explore whether inequalities have changed over time. Our analysis reveals that ethnic differences in health are largely rooted in socioeconomic or spatial difference, although variations by health outcome are observed. This work builds on existing literature which looks to socioeconomic and spatial difference for explanations of ethnic inequalities in health, rather than any supposed inherent underlying risk of poor health for minority ethnic groups

Evaluating the performance of Iterative Proportional Fitting for spatial microsimulation: new tests for an established technique

Iterative Proportional Fitting (IPF), also known as biproportional fitting, ‘raking’ or the RAS algorithm, is an established procedure used in a variety of applications across the social sciences. Primary amongst these for urban modelling has been its use in static spatial microsimulation to generate small area microdata — individual level data allocated to administrative zones. The technique is mature, widely used and relatively straight-forward. Although IPF is well described mathematically, accessible examples of the algorithm written in modern programming languages are rare. Therefore, there is a tendency for researchers to ‘start from scratch’, resulting in a variety of ad hoc implementations and little evidence about the relative merits of different approaches. These knowledge gaps mean that answers to certain methodological questions must be guessed: How can ‘empty cells’ be identified and how do they influence model fit? Can IPF be made more computationally efficient? This paper tackles these questions and more using a systematic methodology with publicly available code and data. The results demonstrate the sensitivity of the results to initial conditions, notably the presence of ‘empty cells’, and the dramatic impact of software decisions on computational efficiency. The paper concludes by proposing an agenda for robust and transparent future tests in the field

The design of mixed-use virtual auditory displays: Recent findings with a dual-task paradigm

Presented at the 10th International Conference on Auditory Display (ICAD2004)In the third of an ongoing series of exploratory sound information display studies, we augmented a dual task with a mixed-use auditory display designed to provide relevant alert information for each task. The tasks entail a continuous tracking activity and a series of intermittent classification decisions that, in the present study, were presented on separate monitors that were roughly 90\,^{\circ} apart. Using a 2-by-3 design that manipulated both the use of sound in each task and where sounds for the decision task were positioned, the following principal questions were addressed: Can tracking performance be improved with a varying auditory alert tied to error? To what degree do listeners use virtual auditory deixis as a cue for improving decision reaction times? Can a previous finding involving participants' use of sound offsets (cessations) be repeated? And, last, are there performance consequences when auditory displays for separate tasks are combined? Respectively, we found that: Tracking performance as measured by RMS error was not improved and was apparently negatively affected by the use of our auditory design. Listener's use of even limited virtual auditory deixis is robust, but it is probably also sensitive to the degree it is coincident with the location of corresponding visual stimuli in the task environment. On the basis of manually collected head movement data, listeners do make opportunistic use of sound offsets. And, finally, a significant interaction, as measured by average participant reaction time, was observed between the auditory display used for one task and the manipulation of the degree of auditory deixis encoded in the auditory display used for the other task in our paradigm

Defining the phenotypes of sickle cell disease.

The sickle cell gene is pleiotropic in nature. Although it is a single gene mutation, it has multiple phenotypic expressions that constitute the complications of sickle cell disease. The frequency and severity of these complications vary considerably both latitudinally in patients and longitudinally in the same patient over time. Thus, complications that occur in childhood may disappear, persist or get worse with age. Dactylitis and stroke, for example, occur mostly in childhood, whereas leg ulcers and renal failure typically occur in adults. It is essential that the phenotypic manifestations of sickle cell disease be defined accurately so that communication among providers and researchers facilitates the implementation of appropriate and cost-effective diagnostic and therapeutic modalities. The aim of this review is to define the complications that are specific to sickle cell disease based on available evidence in the literature and the experience of hematologists in this field

Estimating uncertainty in spatial microsimulation approaches to small area estimation: a new approach to solving an old problem

A wide range of user groups from policy makers to media commentators demand ever more spatially detailed information yet the desired data are often not available at fine spatial scales. Increasingly, small area estimation (SAE) techniques are called upon to fill in these informational gaps by downscaling survey outcome variables of interest based on the relationships seen with key covariate data. In the process SAE techniques both rely extensively on small area Census data to enable their estimation and offer potential future substitute data sources in the event of Census data becoming unavailable. Whilst statistical approaches to SAE routinely incorporate intervals of uncertainty around central point estimates in order to indicate their likely accuracy, the continued absence of such intervals from spatial microsimulation SAE approaches severely limits their utility and arguably represents their key methodological weakness. The present article presents an innovative approach to resolving this key methodological gap based on the estimation of variance of the between-area error term from a multilevel regression specification of the constraint selection for iterative proportional fitting (IPF). The performance of the estimated credible intervals are validated against known Census data at the target small area and show an extremely high level of performance. As well as offering an innovative solution to this long-standing methodological problem, it is hoped more broadly that the research will stimulate the spatial microsimulation community to adopt and build on these foundations so that we can collectively move to a position where intervals of uncertainty are delivered routinely around spatial microsimulation small area point estimates

A 2-year intercomparison of the WAM-Cycle4 and the WAVEWATCH-III wave models implemented within the Mediterranean Sea

In this work we present the implementation of a wave forecast/hindcast system for the Mediterranean Sea at a 1/10º horizontal resolution and we show a first assessment of its performance by inter-comparing model results to observational data time series at selected points for the period 2000-2001. The system which is part of the POSEIDON-II operational system includes the WAM – Cycle4 and the WAVEWATCH-III wave forecast models (implemented within the same region) one way coupled with the non-hydrostatic version of the ETA atmospheric model which provides at 3-hour intervals the necessary wind velocity fields to the wave models. The same system but based on the WAM-Cycle4 wave model, has been used in the past for the production of the Aegean Sea wind and wave Atlas. Overall, the inter-comparison shows that both wave models are rather skilful in predicting the integral wave parameters with significant wave height skill scores in the range 0.85-0.90 and mean period scores in the range 0.77-0.83. It is also evident that WAM model has a tendency to overestimate mean wave periods while the opposite is true for WAVEWATCH-III model. Differences between the two models simulated spectra exist along the main passage of cyclonic systems over the Mediterranean Sea while in the wind seas dominated areas of the basin (the Aegean Sea for example) the two models show almost the same behavior