Matched Pair Calibration for Ranking Fairness

We propose a test of fairness in score-based ranking systems called matched pair calibration. Our approach constructs a set of matched item pairs with minimal confounding differences between subgroups before computing an appropriate measure of ranking error over the set. The matching step ensures that we compare subgroup outcomes between identically scored items so that measured performance differences directly imply unfairness in subgroup-level exposures. We show how our approach generalizes the fairness intuitions of calibration from a binary classification setting to ranking and connect our approach to other proposals for ranking fairness measures. Moreover, our strategy shows how the logic of marginal outcome tests extends to cases where the analyst has access to model scores. Lastly, we provide an example of applying matched pair calibration to a real-word ranking data set to demonstrate its efficacy in detecting ranking bias.Comment: 19 pages, 8 figure

The effects of melatonin versus placebo on delirium in hip fracture patients: study protocol of a randomised, placebo-controlled, double blind trial

<p>Abstract</p> <p>Background</p> <p>With an ageing population, older persons become a larger part of the hospital population. The incidence of delirium is high in this group, and experiencing delirium has major short- and long-term sequelae, which makes prevention crucial. During delirium, a disruption of the sleep-wake cycle is frequently observed. Melatonin plays an important role in the regulation of the sleep-wake cycle, so this raised the hypothesis that alterations in the metabolism of melatonin might play an important role in the development of delirium. The aim of this article is to describe the design of a randomised, placebo controlled double-blind trial that is currently in progress and that investigates the effects of melatonin versus placebo on delirium in older, postoperative hip fracture patients.</p> <p>Methods/Design</p> <p>Acutely hospitalised patients aged 65 years or older admitted for surgical repair of hip fracture are randomised (n = 452) into a treatment or placebo group. Prophylactic treatment consists of orally administered melatonin (3 mg) at 21:00 h on five consecutive days. The primary outcome is the occurrence of delirium, to be diagnosed according to the Confusion Assessment Method, within eight days after start of the study medication. Secondary outcomes are delirium severity, measured by the Delirium Rating Scale; duration of delirium; differences in subtypes of delirium; differences in total length of hospital stay; total dose of antipsychotics and/or benzodiazepine use during delirium; and in-hospital complications. In the twelve-month follow up visit, cognitive function is measured by a Mini-Mental state examination and the Informant Questionnaire on Cognitive Decline in the Elderly. Functional status is assessed with the Katz ADL index score (patient and family version) and grip strength measurement. The outcomes of these assessments are compared to the outcomes that were obtained during admission.</p> <p>Discussion</p> <p>The proposed study will contribute to our knowledge because studies on the prophylactic treatment of delirium with long term follow up remain scarce. The results may lead to a prophylactic treatment for frail older persons at high risk for delirium that is safe, effective, and easily implementable in daily practice.</p> <p>Trial registration</p> <p>Dutch Clinical Trial Registry: <a href="http://www.trialregister.nl/trialreg/admin/rctview.asp?TC=1576">NTR1576</a></p

Spatial Demography and the Epidemiology of Measles

Infectious diseases remain a significant cause of death worldwide, in spite of advances in medical technology and treatment in the last century. The life cycles of infectious diseases depend on host populations producing hospitable conditions for survival and proliferation. Secular demographic events such as births, local contact rates and regional migration are necessary for the persistence of acute immunizing infections. Each chapter uses measles incidence data from pre-vaccination England and Wales to investigate the relationship between disease dynamics and demographic events. In the first chapter, I use the time-series susceptible-infected-recovered (TSIR) model to investigate transmission rates and measles persistence in urban and rural areas. I use a matched-pair analysis to separate the influence of space and population size to isolate the difference in disease dynamics between urban and rural areas. I find that population size, more than population density, influences the size and persistence of outbreaks; however, there is some evidence that population density may impact the transmission of measles. In chapter two, I challenge previous findings that transmission of measles is uncorrelated with population size. I also address the potential of population-correlated bias in TSIR estimates. In this chapter I leverage high volume stochastic simulations in order to determine if biases in estimates of transmission scale with population size. The results indicate that, in general, large populations have higher transmission rates and bias is greatest for small communities where outbreaks are highly stochastic. In the final chapter, I expand on previous frequency domain results by introducing tensor decomposition as a method for analyzing multiple oscillatory time-series simultaneously. Using this method of dimensionality reduction I am able to extract the dominant periodic signals in measles incidence data. I use this descriptive technique to verify a previous finding: the baby boom surge in births in England and Wales resulted in larger annual peaks in incidence. Together these results highlight the close relationship between demography and infectious disease dynamics. Furthermore, they demonstrate the importance of increasing and maintaining vaccination coverage for measles, particularly in an increasingly urban world where local populations and population density continue to rise

Facilitating prospective registration of diagnostic accuracy studies: A STARD initiative

Although the introduction of prospective trial registration policies has been successful in reducing waste in research, diagnostic accuracy studies are rarely registered. We describe why diagnostic accuracy studies should be registered, and where and how this can be done. Advantages of registration include the identification of unpublished studies, prevention of selective outcome reporting, prevention of unnecessary duplication of research, collaboration between researchers, and linkage of study materials..

Daily Walking among Commuters: A Cross-Sectional Study of Associations with Residential, Work, and Regional Accessibility in Melbourne, Australia (2012-2014)

BACKGROUND: Most research on walking for transport has focused on the walkability of residential neighborhoods, overlooking the contribution of places of work/study and the ease with which destinations outside the immediate neighborhood can be accessed, referred to as regional accessibility. OBJECTIVES: We aimed to examine if local accessibility/walkability around place of work/study and regional accessibility are independently and interactively associated with walking. METHODS: A sample of 4,913 adult commuters was derived from a household travel survey in Melbourne, Australia (2012-2014). Local accessibility was measured as the availability of destinations within an formula presented pedestrian network from homes and places of work/education using a local living index [LLI; 0-3 (low), 4-6, 7-9, and 10-12 (high) destinations]. Regional accessibility was estimated using employment opportunity, commute travel time by mode, and public transport accessibility. Every individual&#039;s potential minutes of walking for each level of exposure (observed and counter to fact) were predicted using multivariable regression models including confounders and interaction terms. For each contrast of exposure levels of interest, the corresponding within-individual differences in predicted walking were averaged across individuals to estimate marginal effects. RESULTS: High LLI at home and work/education was associated with more minutes walking than low LLI by 3.9 [95% confidence interval (CI): 2.3, 5.5] and 8.3 (95% CI: 7.3, 9.3) min, respectively, in mutually adjusted models. Across regional accessibility measures, an independent association with walking and an interactive association with LLI at work/education was observed. To take one example, the regional accessibility measure of &quot;Jobs within 30 min by public transport&quot; was associated with 4.3 (95% CI: 2.9, 5.7) more mins walking for high (formula presented ) compared with low (formula presented ) accessibility in adjusted models. Th