Disparate Measures Research Articles

Measuring health disparities: a comparison of absolute and relative disparities.

Monitoring national trends in disparities in different diseases could provide measures to evaluate the impact of intervention programs designed to reduce health disparities. In the US, most of the reports that track health disparities provided either relative or absolute disparities or both. However, these two measures of disparities are not only different in scale and magnitude but also the temporal changes in the magnitudes of these measures can occur in opposite directions. The trends for absolute disparity and relative disparity could move in opposite directions when the prevalence of disease in the two populations being compared either increase or decline simultaneously. If the absolute disparity increases but relative disparity declines for consecutive time periods, the absolute disparity increases but relative disparity declines for the combined time periods even with a larger increase in absolute disparity during the combined time periods. Based on random increases or decreases in prevalence of disease for two population groups, there is a higher chance the trends of these two measures could move in opposite directions when the prevalence of disease for the more advantaged group is very small relative to the prevalence of disease for the more disadvantaged group. When prevalence of disease increase or decrease simultaneously for two populations, the increase or decrease in absolute disparity has to be sufficiently large enough to warrant a corresponding increase or decrease in relative disparity. When absolute disparity declines but relative disparity increases, there is some progress in reducing disparities, but the reduction in absolute disparity is not large enough to also reduce relative disparity. When evaluating interventions to reduce health disparities using these two measures, it is important to consider both absolute and relative disparities and consider all the scenarios discussed in this paper to assess the progress towards reducing or eliminating health disparities.

Measuring rural–urban disparity with the Genuine Progress Indicator: A case study in Japan

Japan, often regarded as one of the world's most egalitarian societies, has faced increasing rural–urban disparity since the late 1980s. However, even if the wages and income levels of rural populations are lower than those of urban residents, some people will remain in the rural areas or, in some cases, return from the cities. These observations imply the necessity of measuring the rural–urban disparity in Japan as well as the need for an alternative indicator to the conventional economic tools for taking this disparity measurement. The objective of this paper is to measure rural–urban disparity with GPI based on a case study in Japan. The results of this analysis present two key findings. First, the rural–urban disparity measured by the GPI is much smaller than that measured by GDP. Second, the GPI disparity has been an increasing trend, particularly after the 2000s, due to the increased cost of climate change in rural areas. GPI can identify some strengths of rural areas that are not captured by GDP, but these advantages are cancelled out by the increasing cost of climate change.

Effects of Prism Eyeglasses on Objective and Subjective Fixation Disparity.

In optometry of binocular vision, the question may arise whether prisms should be included in eyeglasses to compensate an oculomotor and/or sensory imbalance between the two eyes. The corresponding measures of objective and subjective fixation disparity may be reduced by the prisms, or the adaptability of the binocular vergence system may diminish effects of the prisms over time. This study investigates effects of wearing prisms constantly for about 5 weeks in daily life. Two groups of 12 participants received eyeglasses with prisms having either a base-in direction or a base-out direction with an amount up to 8 prism diopters. Prisms were prescribed based on clinical fixation disparity test plates at 6 m. Two dependent variables were used: (1) subjective fixation disparity was indicated by a perceived offset of dichoptic nonius lines that were superimposed on the fusion stimuli and (2) objective fixation disparity was measured with a video based eye tracker relative to monocular calibration. Stimuli were presented at 6 m and included either central or more peripheral fusion stimuli. Repeated measurements were made without the prisms and with the prisms after about 5 weeks of wearing these prisms. Objective and subjective fixation disparity were correlated, but the type of fusion stimulus and the direction of the required prism may play a role. The prisms did not reduce the fixation disparity to zero, but induced significant changes in fixation disparity with large effect sizes. Participants receiving base-out prisms showed hypothesized effects, which were concurrent in both types of fixation disparity. In participants receiving base-in prisms, the individual effects of subjective and objective effects were negatively correlated: the larger the subjective (sensory) effect, the smaller the objective (motor) effect. This response pattern was related to the vergence adaptability, i.e. the individual fusional vergence reserves.

P01.09 Trends in selected measures of racial and ethnic disparities in gonorrhoea and syphilis in the united states, 1981–2012

<h3>Introduction</h3> The purpose of this study was to examine different measures of racial and ethnic disparities in the reported cases of primary and secondary (P&amp;S) syphilis and gonorrhoea from 1981 to 2012 in the United States. <h3>Methods</h3> For each year from 1981 to 2012, we calculated values for five disparity measures: the Gini coefficient, two versions of the index of disparity (unweighted and weighted by population subgroup size), the population attributable fraction, and the black-to-white rate ratio. We also examined annual changes in these measures. Specifically, we examined whether or not the five measures yielded consistent assessments as to whether racial and ethnic disparity was increasing or decreasing from one year to the next. <h3>Results</h3> Overall, the disparity measures we examined were generally consistent with one another. However, from any given year to the next, the various disparity measures could yield divergent results in terms of whether racial/ethnic disparities in STDs are increasing or decreasing as well as in terms of the relative magnitude of the change. Over the 31-year period, ≥4 of the 5 index measures agreed on the direction of change 28 times for both P&amp;S syphilis and gonorrhoea. The most common measure that had a different direction of change from the other measures was the population attributable fraction. <h3>Conclusion</h3> Our findings illustrated two well-known limitations of relative measures of racial/ethnic disparities in health. First, relative measures of disparity can decrease due to increases in STD incidence rates among Non-Hispanic Whites (or increase due to decreases in STD incidence among Non-Hispanic Whites). Second, whether or not racial and ethnic disparities increased from one year to the next can differ across measures of disparity. Reliance on just one measure of disparity can at times lead to divergent conclusions about changes in disparities over short time periods. <h3>Disclosure of interest statement</h3> The findings and conclusions in this study are those of the authors and do not necessarily represent the official position of the United States Centres for Disease Control and Prevention (CDC). No external funding was received for this study and the authors have no conflicts of interest.

S05.5 Network formation as a determinant of spatial disparity

<h3>Introduction</h3> Racial disparities in the burden of sexually transmitted disease have been documented and described for decades. Several disparity measures, such as the black-to-white rate ratio, the Index of Disparity (ID), and the Gini coefficient, have been used to quantify disparities in STDs. Although these measures are generally useful and informative, in some scenarios the results of these measures may seem incongruous with reasonable, practical assessments of disparity. The purpose of this study was to provide examples of such incongruities in the context of racial disparities in STDs. <h3>Methods</h3> We examined a population consisting of 312.5 million people overall, with 200 million non-Hispanic Whites, 40 million non-Hispanic Blacks, 55 million Hispanics, 15 million Asian/Pacific Islanders, and 2.5 million American Indian/Alaskan Natives (AI/AN), similar to the actual US population. Case numbers of a hypothetical STD for each racial group were chosen arbitrarily (yet purposefully) to yield illustrations of potential incongruities among disparity measures. <h3>Results</h3> We found several hypothetical examples of incongruities among disparity measures. For example, the ID was about ten times higher when all STD cases occurred among AI/AN than when all cases occurred among non-Hispanic Blacks. As another example, the ID indicated that disparity was less when all STD cases occurred among non-Hispanic Blacks than when each of the five racial groups accounted for one fifth of all STD cases. <h3>Conclusion</h3> Relative measures of racial disparity in STDs can be useful to illustrate the burden of disparity, to assess trends, and to inform the targeting of prevention resources. However, in some scenarios the disparity measures can be incongruous with reasonable, practical assessments of disparity, such as when the ID is biased against non-Hispanic Blacks. The ID is more prone to these incongruities than measures which account for population size, such as the Gini coefficient or the weighted ID. <h3>Disclosure of interest statement</h3> The authors have no conflicts to declare. No pharmaceutical grants were received in the development of this study.

S05.4 Potential incongruities in relative measures of disparities in sexually transmitted diseases

Sexually transmitted infections (STIs) in pregnancy prevalent in many resource limited settings are associated with adverse pregnancy outcomes that include spontaneous abortion, stillbirths, preterm rupture of membranes, premature delivery and postpartum endometritis. Antenatal clinic attendance provides opportunity to screen the women for STIs, offer prompt treatment for curable STIs or prophylaxis for viral infections such as HIV and to promote prevention. Although routine screening for syphilis and HIV is recommended as part of antenatal care (ANC), optimal screening rates have not been achieved. This is due antenatal clinic non-attendance, non-availability of screening tests and where available, health system inefficiencies such long wait time before test results are available or need for women to make return visits to receive results. Use of point-of care tests that detect syphilis and HIV have been shown to increase the number of women tested for HIV and syphilis, are inexpensive, easy to use and do not require a sophisticated laboratory. In resource limited settings, prompt detection and treatment of the other STIs is hampered by lack of screening tests. Often, health providers rely on syndromic approach to diagnose and manage STIs. This approach alleviates the need for laboratory services but misses women with asymptomatic infections and has poor diagnostic performance. Pregnant women with STIs are at an increased risk of acquiring HIV and transmitting the infection to their infants. Increased availability of HIV testing and provision of effective PMTCT regimens has dramatically reduced the number of new paediatric HIV infections. However, STIs, apart from HIV, have not been viewed as a public health priority and adequate resources allocated to combat them. To optimise maternal and infant outcomes, there is need to prioritise development of low-cost tests to detect STIs during pregnancy and to ensure women are provided with effective treatment promptly.

Disparities in cardiovascular disease among Caribbean populations: a systematic literature review.

BackgroundCardiovascular diseases (CVD) are the predominant cause of death globally. The large health disparities in the distribution of the burden of disease seen in developed and developing countries are of growing concern. Central to this concern is the poor outcome which is seen disproportionately in socially disadvantaged groups and racial/ethnic minorities. The aim of the study was to conduct a systematic literature review to investigate the nature of cardiovascular disease health disparities among Afro-Caribbean origin populations and identify current knowledge gaps.MethodsA systematic literature review including a detailed search strategy was developed to search MEDLINE and other research databases. Using an a priori protocol peer-reviewed publications and grey literature articles were retrieved and screened and relevant data extracted by two independent review authors. Thematic analysis was done according to CVD outcomes and measures of disparity including age, sex, ethnicity and socioeconomic status.ResultsThe search retrieved 665 articles of which 22 met the inclusion criteria. Most studies were conducted in the United Kingdom and centered on the prevalence of CVD by ethnicity, age and sex. An important sub-theme identified was the disparities in health service utilization/hospital admission. Coronary Heart Disease (CHD) and Peripheral Arterial Disease (PAD) were less prevalent among Afro-Caribbeans compared to Caucasian and South East Asian ethnic groups. The prevalence of CHD ranged from 0–7 % in Afro-Caribbean to 2–22 % in Caucasians. Strokes were more common among Afro-Caribbeans. There are inadequate data on morbidity and mortality from CVD, particularly across the socio-economic gradient, in Afro-Caribbean populations.ConclusionsThere are important differences in morbidity and mortality from CVD across ethnic groups. Important knowledge gaps remain in understanding the social determinants of these disparities in CVD. More research exploring these gaps by varying disparity indicators needs to be undertaken.Electronic supplementary materialThe online version of this article (doi:10.1186/s12889-015-2166-7) contains supplementary material, which is available to authorized users.

Hormonal and intrauterine methods for contraception for women aged 25 years and younger.

Women between the ages of 15 and 24 years have high rates of unintended pregnancy; over half of women in this age group want to avoid pregnancy. However, women under age 25 years have higher typical contraceptive failure rates within the first 12 months of use than older women. High discontinuation rates may also be a problem in this population. Concern that adolescents and young women will not find hormonal or intrauterine contraceptives acceptable or effective might deter healthcare providers from recommending these contraceptive methods. To compare the contraceptive failure (pregnancy) rates and to examine the continuation rates for hormonal and intrauterine contraception among young women aged 25 years and younger. We searched until 4 August 2015 for randomized controlled trials (RCTs) that compared hormonal or intrauterine methods of contraception in women aged 25 years and younger. Computerized databases included the Cochrane Register of Controlled Trials (CENTRAL), MEDLINE, EMBASE, POPLINE, CINAHL, and LILACS. We also searched for current trials via ClinicalTrials.gov and the International Clinical Trials Registry Platform (ICTRP). We considered RCTs in any language that reported the contraceptive failure rates for hormonal or intrauterine contraceptive methods, when compared with another contraceptive method, for women aged 25 years and younger. The other contraceptive method could have been another intrauterine contraceptive, another hormonal contraceptive or different dose of the same method, or a non-hormonal contraceptive. Treatment duration must have been at least three months. Eligible trials had to include the primary outcome of contraceptive failure rate (pregnancy). The secondary outcome was contraceptive continuation rate. One author conducted the primary data extraction and entered the information into Review Manager. Another author performed an independent data extraction and verified the initial entry. For dichotomous outcomes, we computed the Mantel-Haenszel odds ratio (OR) with 95% confidence interval (CI). Because of disparate interventions and outcome measures, we did not conduct meta-analysis. Five trials met the inclusion criteria. The studies included a total of 1503 women, with a mean of 301 participants. The trials compared the following contraceptives: combined oral contraceptive (COC) versus transdermal contraceptive patch, vaginal contraceptive ring, or levonorgestrel intrauterine system 20 µg/day (LNG-IUS 20); LNG-IUS 12 µg/day (LNG-IUS 12) versus LNG-IUS 16 µg/day (LNG-IUS 16); and LNG-IUS 20 versus the copper T380A intrauterine device (IUD). In the trials comparing two different types of methods, the study arms did not differ significantly for contraceptive efficacy or continuation. The sample sizes were small for two of those studies. The only significant outcome was that a COC group had a higher proportion of women who discontinued for 'other personal reasons' compared with the group assigned to the LNG-IUS 20 (OR 0.27, 95% CI 0.09 to 0.85), which may have little clinic relevance. The trial comparing LNG-IUS 12 versus LNG-IUS 16 showed similar efficacy over one and three years. In three trials that examined different LNG-IUS, continuation was at least 75% at 6 to 36 months. We considered the overall quality of evidence to be moderate to low. Limitations were due to trial design or limited reporting. Different doses in the LNG-IUS did not appear to influence efficacy over three years. In another study, continuation of the LNG-IUS appeared at least as high as that for the COC. The current evidence was insufficient to compare efficacy and continuation rates for hormonal and intrauterine contraceptive methods in women aged 25 years and younger.

Monocular Versus Binocular Calibrations in Evaluating Fixation Disparity With a Video-Based Eye-Tracker.

When measuring fixation disparity (an oculomotor vergence error), the question arises as to whether a monocular or binocular calibration is more precise and physiologically more appropriate. In monocular calibrations, a single eye fixates on a calibration target that is taken as having been projected onto the center of the fovea; the corresponding vergence state represents the heterophoria (the resting vergence position), which has no effect on the calibration procedure. In binocular calibrations, a vergence error may be present and may affect the subsequent measurement of the fixation disparity during binocular recordings. This study includes a test of the precision of both monocular and binocular calibrations and an evaluation of the impact of the calibration procedure on the measurement of fixation disparity during a dot scanning task. Our results show that 11 participants (out of 19) each exhibited a significant difference in fixation disparity with the two types of calibration procedures. In addition, the fixation disparity was more strongly affected by heterophoria undergoing monocular calibration, as opposed to binocular calibration. This serves as additional evidence showing that the monocular calibration produces a physiologically more plausible fixation disparity and seems to be more appropriate for studying the full extent of fixation disparity.

Lessons From 20 Years of Human–Elephant Conflict Mitigation in Africa

The further refinement and re-assessment of human–elephant conflict (HEC) mitigation methods that has occurred since 2003 can be summarized into biological, physical, and governance categories. The most important distinction is between those measures applied against animals and used within the conflict zone, which are mostly used in the shorter term (except some fencing), and those measures working with people in the longer term, which rely heavily on official policy and administration often situated beyond the conflict zone. Effective HEC mitigation is difficult to understand and problematic to implement; it remains a complex package of apparently disparate measures that have to be used in combination and flexibly, at different scales, for both animals and people. Future HEC mitigation will be as much an art as a science, but since we now have a solid research foundation, we can proceed with some confidence to address the inherent sociopolitical difficulties.

A global perspective on the epidemiology of acne.

Acne is estimated to affect 9.4% of the global population, making it the eighth most prevalent disease worldwide. Epidemiological studies have demonstrated that acne is most common in postpubescent teens, with boys most frequently affected, particularly with more severe forms of the disease. This paper aims to provide an update on the epidemiology of acne worldwide. Recent general and institutional studies from around the world have shown that the prevalence of acne is broadly consistent globally (with the exception of specific populations, which are discussed). However, this review highlights that there is a wide range of disparate outcome measures being applied in epidemiology studies, and we emphasize the need to develop a widely accepted, credible, standard assessment scale to address this in the future. In addition we discuss special populations, such as those devoid of acne, as well as the impact of potential determinants of acne on disease epidemiology.

Relationships of diversity, disparity, and their evolutionary rates in squirrels (Sciuridae).

Several theories predict that rapidly diversifying clades will also rapidly diverge phenotypically; yet, there are also reasons for suspecting that diversification and divergence might not be correlated. In the widely distributed squirrel clade (Sciuridae), we test for correlations between per lineage speciation rates, species richness, disparity, and a time-invariant measure of disparity that allows for comparing rates when evolutionary modes differ, as they do in squirrels. We find that species richness and speciation rates are not correlated with clade age or with each other. Disparity appears to be positively correlated with clade age because young, rapidly diversifying Nearctic grassland clades are strongly pulled to a single stable optimum but older, slowly diversifying Paleotropical forest clades contain lineages that diverge along multiple ecological and morphological lines. That contrast is likely due to both the environments they inhabit and their phylogenetic community structure. Our results argue against a shared explanation for diversity and disparity in favor of geographically mediated modes of speciation and ecologically mediated modes of phenotypic evolution.

Sustained Reduction in Health Disparities Achieved through Targeted Quality Improvement: One-Year Follow-up on a Three-Year Intervention.

To assess a quality improvement disparity reduction intervention and its sustainability. Electronic health records and Quality Index database of Clalit Health Services in Israel (2008-2012). Interrupted time-series with pre-, during, and postintervention disparities measurement between 55 target clinics (serving approximately 400,000 mostly low socioeconomic, minority populations) and all other (126) clinics. Data on a Quality Indicator Disparity Scale (QUIDS-7) of 7 indicators, and on a 61-indicator scale (QUIDS-61). The gap between intervention and nonintervention clinics for QUIDS-7 decreased by 66.7 percent and by 70.4 percent for QUIDS-61. Disparity reduction continued (18.2 percent) during the follow-up period. Quality improvement can achieve significant reduction in disparities in a wide range of clinical domains, which can be sustained over time.

Dense point-cloud representation of a scene using monocular vision

We present a three-dimensional (3-D) reconstruction system designed to support various autonomous navigation applications. The system presented focuses on the 3-D reconstruction of a scene using only a single moving camera. Utilizing video frames captured at different points in time allows us to determine the depths of a scene. In this way, the system can be used to construct a point-cloud model of its unknown surroundings. We present the step-by-step methodology and analysis used in developing the 3-D reconstruction technique. We present a reconstruction framework that generates a primitive point cloud, which is computed based on feature matching and depth triangulation analysis. To populate the reconstruction, we utilized optical flow features to create an extremely dense representation model. With the third algorithmic modification, we introduce the addition of the preprocessing step of nonlinear single-image super resolution. With this addition, the depth accuracy of the point cloud, which relies on precise disparity measurement, has significantly increased. Our final contribution is an additional postprocessing step designed to filter noise points and mismatched features unveiling the complete dense point-cloud representation (DPR) technique. We measure the success of DPR by evaluating the visual appeal, density, accuracy, and computational expense and compare with two state-of-the-art techniques.

Impact of the terrestrial-aquatic transition on disparity and rates of evolution in the carnivoran skull.

BackgroundWhich factors influence the distribution patterns of morphological diversity among clades? The adaptive radiation model predicts that a clade entering new ecological niche will experience high rates of evolution early in its history, followed by a gradual slowing. Here we measure disparity and rates of evolution in Carnivora, specifically focusing on the terrestrial-aquatic transition in Pinnipedia. We analyze fissiped (mostly terrestrial, arboreal, and semi-arboreal, but also including the semi-aquatic otter) and pinniped (secondarily aquatic) carnivorans as a case study of an extreme ecological transition. We used 3D geometric morphometrics to quantify cranial shape in 151 carnivoran specimens (64 fissiped, 87 pinniped) and five exceptionally-preserved fossil pinnipeds, including the stem-pinniped Enaliarctos emlongi. Range-based and variance-based disparity measures were compared between pinnipeds and fissipeds. To distinguish between evolutionary modes, a Brownian motion model was compared to selective regime shifts associated with the terrestrial-aquatic transition and at the base of Pinnipedia. Further, evolutionary patterns were estimated on individual branches using both Ornstein-Uhlenbeck and Independent Evolution models, to examine the origin of pinniped diversity.ResultsPinnipeds exhibit greater cranial disparity than fissipeds, even though they are less taxonomically diverse and, as a clade nested within fissipeds, phylogenetically younger. Despite this, there is no increase in the rate of morphological evolution at the base of Pinnipedia, as would be predicted by an adaptive radiation model, and a Brownian motion model of evolution is supported. Instead basal pinnipeds populated new areas of morphospace via low to moderate rates of evolution in new directions, followed by later bursts within the crown-group, potentially associated with ecological diversification within the marine realm.ConclusionThe transition to an aquatic habitat in carnivorans resulted in a shift in cranial morphology without an increase in rate in the stem lineage, contra to the adaptive radiation model. Instead these data suggest a release from evolutionary constraint model, followed by aquatic diversifications within crown families.Electronic supplementary materialThe online version of this article (doi:10.1186/s12862-015-0285-5) contains supplementary material, which is available to authorized users.

Racial disparities in the type of postmastectomy reconstruction chosen

BackgroundRacial disparities remain for women undergoing immediate breast reconstruction (IBR) after mastectomy. Understanding patterns of racial disparities in IBR utilization may present opportunities to tailor policies aimed at optimizing care across racial groups. The aim of this study was to determine if racial disparities exist for types of IBR chosen. MethodsA national, retrospective cohort study used the 2005–2011 American College of Surgeons National Surgical Quality Improvement Program database. Multivariable logistic regression models were created to detect the odds by race for receiving each subtype of IBR after mastectomy—prosthetic, pedicled-transfer autologous tissue, or free-transfer autologous tissue. Secondary outcome was trends in IBR rates over time. ResultsThere were 44,597 women identified in the data set who underwent mastectomy. Thirty-seven percent of women (N = 16, 642) were noted to undergo IBR after mastectomy. Prosthetic reconstruction (84.4%, n = 37, 640) was the most common form of IBR compared with pedicled-autologous reconstruction (15.4%, n = 6868) and free transfer autologous reconstruction (4.9%, n = 2185), P < 0.001. In multivariate analysis, minorities had lower odds of undergoing IBR compared with whites (odds ratio [OR] 0.37 and 95% confidence interval [CI] 0.33–0.42 for Asians, OR 0.57 and 95% CI 0.52–0.61 for blacks, and OR 0.64 and 95% CI 0.58–0.71 for Hispanics, all P < 0.001). Compared with whites, Hispanics (OR 0.70, 95% CI 0.58–0.83) and blacks (OR 0.53, 95% CI 0.46–0.60) were less likely to use prosthetic reconstruction and more likely to use free-transfer autologous reconstruction (OR 1.66, 95% CI 1.26–2.18 for Hispanics, OR 2.13, 95% CI 1.73–2.63 for blacks), all P < 0.001. Racial disparities persisted from 2005–2011; as minority patients were less likely to undergo IBR than whites (P < 0.001). ConclusionsUtilization of IBR may be a sensitive measure of disparities in access to high-quality care and underlying cultures. Strategies aimed at reducing racial disparities in IBR should be tailored to specific patterns of disparities among Asian, black, and Hispanic women.

Defining an 2-disparity Measure to Check and Improve the Geometric Accuracy of Non-interpolating Curved High-order Meshes

We define an ▪2-disparity measure between curved high-order meshes and parameterized manifolds in terms of an ▪2 norm. The main application of the proposed definition is to measure and improve the distance between a curved high-order mesh and a target parameterized curve or surface. The approach allows considering meshes with the nodes on top of the curve or surface (interpolative), or floating freely in the physical space (non-interpolative). To compute the disparity measure, the average of the squared point-wise differences is minimized in terms of the nodal coordinates of an auxiliary parametric high-order mesh. To improve the accuracy of approximating the target manifold with a non-interpolating curved high-order mesh, we minimize the square of the disparity measure expressed both in terms of the nodal coordinates of the physical and parametric curved high-order meshes. The proposed objective functions are continuously differentiable and thus, we are able to use minimization algorithms that require the first or the second derivatives of the objective function. Finally, we present several examples that show that the proposed methodology generates high-order approximations of the target manifold with optimal convergence rates for the geometric accuracy even when non-uniform parameterizations of the manifolds are prescribed. Accordingly, we can generate coarse curved high-order meshes significantly more accurate than finer low-order meshes that feature the same resolution.

Optimizing Data Management with Disparities in Data Value

ABSTRACT When there is a disparity in the value of different data records and fields, there is a need for an optimization of data resources. Not all data necessarily contribute the same value. It depends on the usage of the data, as well as a variety of other factors. This paper presents models for optimizing data management in the presence of a disparity between the values contributed by different data. We expound on what disparity of data value represents and illustrate models to derive a numerical measure of such disparity. We then use real-world data from a large data resource used to manage alumni relations, and demonstrate our optimization methods and results. We then discuss the tradeoffs involved between value and cost, and the implications for data management, both in this real-world context and in general. KEYWORDS: Disparity, Data Value, Data Management, Optimization INTRODUCTION Organizations make large investments in technology to manage data, a critical organizational resource. In making these investments organizations have to carefully evaluate the information systems and technology that are used to manage the data. Typically, such evaluations are primarily based on technical requirements such as storage capacities and processing speeds and on functional requirements such as presentation formats (e.g., dashboards and visualization) and business needs such as speed of delivery and search capabilities. In this paper, we suggest that evaluating data management systems must consider yet another perspective, economic aspects. In no way minimizing the importance of technical and functional aspects, we suggest that the design and management of data resources ought to also consider the cost-benefit tradeoffs associated with managing data resources. To emphasize this perspective we argue that all data should not be treated as contributing equally to the benefit derived from using a data resource and that some records in a dataset may contribute more to benefit than others. We refer to this as disparity in the value derived from the data (or value disparity). We believe that understanding value disparity and the associated value/cost tradeoffs, has important implications for data management. Not only can it impact how we use data, it can also impact the design and management of data resources and associated information systems. We examine value disparity in a large data resource used to manage alumni relations. Using this as a context, we first evaluate value disparity and show that it is significantly large in this data resource. We then describe the current data acquisition and management policies, discuss the relationship between the policies and the value disparity identified, and in this context, highlight related implications for data management including how the data resource may be optimized considering an economic perspective. The rest of the paper is organized as follows. First we describe the research relevant to value/cost tradeoffs in data management to define the scope of our research. We then develop our models for assessing the magnitude of value disparity. We further illustrate the application of our models using sizable samples from the data resource for managing alumni relations. We finally discuss the implications of understanding value disparity for data management and conclude with a discussion on the limitations of our research. BACKGROUND Managing data efficiently and effectively helps organizations realize the business value of the data. Data contributes to business value in multiple different ways. Data supports managing operational activities such as tracking supply chain activities (Gattiker & Goodhue, 2004) and customer relationships (Roberts and Berger, 1999). Data also helps organizations gain competitive advantage through analytics (Davenport, 2006) and decision support (March & Hevner, 2007, Ramakrishnan et al. …

A morphospace of planktonic marine diatoms. II. Sampling standardization and spatial disparity partitioning

AbstractMorphospace occupation through time provides a view of diversification distinct from the more familiar taxonomic tabulations. However, this view is subject to the same geological biases long recognized in studies of taxonomic diversification, where techniques for correcting secular bias in sampling have become standard practice. In this study, we apply sampling standardization techniques to a morphospace investigation to test whether observed stratigraphic trends in morphospace occupation are artifacts of trends in sampling. When sampling bias is corrected by randomized subsampling, all disparity metrics show stationary patterns, or at most directional changes of small magnitude. Metrics describing the average dispersion of taxa in morphospace are less subject to sampling bias than those describing the total extent of morphospace occupied. We also investigate a measure of disparity that is insensitive to sampling intensity, introducing a geographic component of morphological disparity. By analogy to α and β components of taxonomic diversity, we suggest the notions of α and β disparity, and find that α disparity remains roughly constant through time. Our analysis also allows us to present the first taxonomic diversity curve of diatoms under shareholder quorum subsampling (SQS), showing similar results to previously published subsampling methods: a roughly twofold rise over the Cenozoic, with peak diversity around the Eocene/Oligocene boundary. Tests for methodological bias from choices in ordination method and data culling during morphospace construction indicate that our results are relatively insensitive to both factors: Cenozoic occupation of planktonic diatom morphospace is largely unchanging. We find a similarly stationary pattern when we directly analyze the morphological data, seeing no change in the prevalence of taxa with different sets of morphological characters. More broadly, our results make clear that a complete view of morphological disparity must consider sampling biases, which can be addressed with wellestablished, quantitative methods in morphospaces populated using occurrence-level data.

Limits to Arbitrage and Mispricing in TIPS

This paper examines limits to arbitrage and mispricing in Treasury protected securities (TIPS). To this end, I construct two different measures of disparity in bond prices from the smooth yield curve. I find that deviations in prices are highly correlated for different maturities and also between nominal Treasury bonds and TIPS. This suggests that arbitrage capital is efficiently allocated across markets and also along the yield curve. I then study the relative mispricing of nominal bonds and TIPS. While flight-to-liquidity explains well the mispricing for nominal bonds it does not for TIPS. In fact, TIPS mispricing is driven by short-term Treasury bond liquidity and the slope of the term structure of expected inflation. Moreover, TIPS mispricing predicts short-term excess returns of TIPS during the crises. This findings can be rationalized with investors who opt for more liquid nominal bonds whenever the short-term expected inflation is very low, i.e. short-term nominal bonds and short-term TIPS are close to perfect substitutes.