Percentile Points Research Articles

724: Large-for-gestational age and long-term cognitive function

Newborns with growth restriction have been found to be at risk of cognitive delay. We sought to determine if there is cognitive delay among newborns who are large-for-gestational age [LGA; birthweight ≥ 90% for weight for gestational age (WGA)] vs. those who are not. The nationally-representative Early Childhood Longitudinal Study -Birth Cohort (ECLS-B; US Center for Education Statistics) data set was utilized to identify non-anomalous, singletons with birthweight ≥ vs. < 90%. An additional analysis compared cognitive function among newborns ≥ vs. < 95%. Cognitive and academic functioning was measured at four time points: 9 months, 2 years, 3.5 years, and 5.5 years. The association between high WGA and cognitive functioning at each time point was examined using a series of confounder-adjusted General Linear Models (GLM) based methods, to best characterize the potential developmental impact of high WGA. Of 3,043 cases that met criteria, 267 (9.6%) were ≥ 90% WGA. In terms of cognitive performance, children who were ≥ 90% WGA were not statistically different from children between 5%-89% WGA at 9 months, 2 years, Preschool (3.5 years), or Kindergarten (5.5 years) time points (F (1, 2794) = 5.107, p = .068), nor did they change at different rates across early childhood (Wilk's λ (3, 2792) = 0.600, p = .615). The sample size of 3,043 permitted .80 power at α = .05 to detect differences as small as 7.1 percentile points around typical (50th percentile) performance, with greater sensitivity at extreme values. The 95th percentile cut point yielded similar results. There is no difference in cognitive function in children with birthweight ≥ vs. < 90% for gestational age. The long-term risk for LGA infants remains metabolic (i.e. obesity and diabetes).

725: Maternal vitamin D status and risk of preeclampia: a systematic review and meta-analysis

WGA at 9 months, 2 years, Preschool (3.5 years), or Kindergarten (5.5 years) time points (F (1, 2794) 5.107, p .068), nor did they change at different rates across early childhood (Wilk’s (3, 2792) 0.600, p .615). The sample size of 3,043 permitted .80 power at .05 to detect differences as small as 7.1 percentile points around typical (50th percentile) performance, with greater sensitivity at extreme values. The 95th percentile cut point yielded similar results. CONCLUSION: There is no difference in cognitive function in children with birthweight vs. 90% for gestational age. The long-term risk for LGA infants remains metabolic (i.e. obesity and diabetes).

Pulmonary ventilation visualized using hyperpolarized helium-3 and xenon-129 magnetic resonance imaging: differences in COPD and relationship to emphysema

In subjects with chronic obstructive pulmonary disease (COPD), hyperpolarized xenon-129 ((129)Xe) magnetic resonance imaging (MRI) reveals significantly greater ventilation defects than hyperpolarized helium-3 ((3)He) MRI. The physiological and/or morphological determinants of ventilation defects and the differences observed between hyperpolarized (3)He and (129)Xe MRI are not yet understood. Here we aimed to determine the structural basis for the differences in ventilation observed between (3)He and (129)Xe MRI in subjects with COPD using apparent diffusion coefficients (ADC) and computed tomography (CT). Ten COPD ex-smokers provided written, informed consent and underwent MRI, CT, spirometry, and plethysmography. (3)He and (129)Xe MRI ventilation volume was generated using semiautomated segmentation, and ADC maps were registered to generate ADC values for lung regions of interest ventilated by both gases (ADCHX) and by (3)He gas only (ADCHO). CT wall area percentage and the lowest 15th percentile point of the CT lung density histogram (HU15%) were also evaluated. For lung regions accessed by (3)He gas only, mean (3)He ADCHO was significantly greater than for regions accessed by both gases (ADCHO = 0.503 ± 0.119 cm(2)/s, ADCHX = 0.470 ± 0.125 cm(2)/s, P < 0.0001). The difference between (3)He and (129)Xe ventilation volume was significantly correlated with CT HU15% (r = -65, P = 0.04) and (3)He ADCHO (r = 0.70, P = 0.02), but not CT wall area percentage (r = -0.34, P = 0.33). In conclusion, in this small study in COPD subjects, we observed significantly decreased (129)Xe MRI ventilation compared with (3)He MRI, and these regions of decreased (129)Xe ventilation were spatially and significantly correlated with regions of increased pulmonary emphysema, but not airway wall thickness.

Group Cohesion and Performance

Past research examining group cohesion and performance was reviewed using meta analysis. The results indicated a positive relationship with the average cohesive group performing 18 percentile points above the average noncohesive group. Given the nature of the studies used here (all studies had been previously published), caution is suggested in generalizing these results to “real” work groups.

Nonparametric Progressive Mean Control Chart for Monitoring Process Target

Nonparametric control charts are widely used when the parametric distribution of the quality characteristic of interest is questionable. In this study, we proposed a nonparametric progressive mean control chart, namely the nonparametric progressive mean chart, for efficient detection of disturbances in process location or target. The proposed chart is compared with the recently proposed nonparametric exponentially weighted moving average and nonparametric cumulative sum charts using different run length characteristics such as the average run length, standard deviation of the run length, and the percentile points of the run length distribution. The comparisons revealed that the proposed chart outperformed recent nonparametric exponentially weighted moving average and nonparametric cumulative sum charts, in terms of detecting the shifts in process target. A real life example concerning the fill heights of soft drink beverage bottles is also provided to illustrate the application of the proposed nonparametric control chart. Copyright © 2012 John Wiley &amp; Sons, Ltd.

Timing of Stimulant Treatment for ADHD and Effect on Academic Progress

Investigators at University of Iceland, Reykjavik, and other centers in Iceland and in USA studied the probability of academic decline (drop of >5.0 percentile points) in ADHD children according to drug exposure and timing of treatment start between National Scholastic Examinations.

Fourier Series Approximation for Max Operation in Non-Gaussian and Quadratic Statistical Static Timing Analysis

The most challenging problem in the current block-based statistical static timing analysis (SSTA) is how to handle the max operation efficiently and accurately. Existing SSTA techniques suffer from limited modeling capability by using a linear delay model with Gaussian distribution, or have scalability problems due to expensive operations involved to handle non-Gaussian variation sources or nonlinear delays. To overcome these limitations, we propose efficient algorithms to handle the max operation in SSTA with both quadratic delay dependency and non-Gaussian variation sources simultaneously. Based on such algorithms, we develop an SSTA flow with quadratic delay model and non-Gaussian variation sources. All the atomic operations, max and add, are calculated efficiently via either closed-form formulas or low dimension (at most 2-D) lookup tables. We prove that the complexity of our algorithm is linear in both variation sources and circuit sizes, hence our algorithm scales well for large designs. Compared to Monte Carlo simulation for non-Gaussian variation sources and nonlinear delay models, our approach predicts the mean, standard deviation and 95% percentile point with less than 2% error, and the skewness with less than 10% error.

Assessment of Pulmonary Neutrophilic Inflammation in Emphysema by Quantitative Positron Emission Tomography

Neutrophilic inflammation is understood to be of pathogenetic importance in chronic obstructive pulmonary disease (COPD) and may be quantified using 18-fluorodeoxyglucose positron emission tomography-computed tomography ((18)FDG PET-CT) as a noninvasive, spatially informative biomarker. To assess the potential usefulness of (18)FDG PET-CT as a surrogate measure of pulmonary neutrophilic inflammation in patients with usual COPD and α(1)-antitrypsin deficiency (AATD). (18)FDG PET-CT imaging was performed in 10 patients with usual COPD, 10 patients with AATD, and 10 healthy control subjects. Pulmonary (18)FDG uptake was estimated by three-dimensional Patlak graphical analysis as an indicator of pulmonary neutrophilic glycolytic activity. Patients with AATD were treated with 12 weekly intravenous infusions of AAT augmentation therapy before repeat imaging. (18)FDG uptake, lung physiology, lung density, and systemic markers of inflammation were compared for all groups at baseline and, in patients with AATD, at baseline and on treatment. (18)FDG uptake in the upper lung of patients with usual COPD was greater compared with the healthy control group (P = 0.009) and correlated with measures of disease severity (FEV(1)% predicted, r = -0.848, P = 0.001; FEV(1)/FVC, r = -0.918, P < 0.001; Kco% predicted, r = -0.624, P = 0.027; 15th percentile point, r = -0.709, P = 0.011). No significant difference was observed between measurements at baseline and on treatment in patients with AATD. Quantitative (18)FDG PET-CT has a potential role as an imaging biomarker in mechanistic and interventional studies in patients with usual COPD. The data support previous evidence of distinct functional characteristics of neutrophils in COPD. Clinical trial registered with https://eudract.ema.europa.eu/index.html (EudraCT 2007-004869-18).

Early to rise? The effect of daily start times on academic performance

Local school districts often stagger daily start times for their schools in order to reduce busing costs. This paper uses data on all middle school students in Wake County, NC from 1999 to 2006 to identify the causal effect of daily start times on academic performance. Using variation in start times within schools over time, the effect is a two percentile point gain in math test scores – roughly fourteen percent of the black–white test score gap. I find similar results for reading scores and using variation in start times across schools. The effect is stronger for students in the lower end of the distribution of test scores. I find evidence supporting increased sleep as a mechanism through which start times affect test scores. Later start times compare favorably on cost grounds to other education interventions which result in similar test score gains.

A Population-Based Study of Stimulant Drug Treatment of ADHD and Academic Progress in Children

We evaluated the hypothesis that later start of stimulant treatment of attention-deficit/hyperactivity disorder adversely affects academic progress in mathematics and language arts among 9- to 12-year-old children. We linked nationwide data from the Icelandic Medicines Registry and the Database of National Scholastic Examinations. The study population comprised 11,872 children born in 1994-1996 who took standardized tests in both fourth and seventh grade. We estimated the probability of academic decline (drop of ≥ 5.0 percentile points) according to drug exposure and timing of treatment start between examinations. To limit confounding by indication, we concentrated on children who started treatment either early or later, but at some point between fourth-grade and seventh-grade standardized tests. In contrast with nonmedicated children, children starting stimulant treatment between their fourth- and seventh-grade tests were more likely to decline in test performance. The crude probability of academic decline was 72.9% in mathematics and 42.9% in language arts for children with a treatment start 25 to 36 months after the fourth-grade test. Compared with those starting treatment earlier (≤ 12 months after tests), the multivariable adjusted risk ratio (RR) for decline was 1.7 (95% confidence interval [CI]: 1.2-2.4) in mathematics and 1.1 (95% CI: 0.7-1.8) in language arts. The adjusted RR of mathematics decline with later treatment was higher among girls (RR, 2.7; 95% CI: 1.2-6.0) than boys (RR, 1.4; 95% CI: 0.9-2.0). Later start of stimulant drug treatment of attention-deficit/hyperactivity disorder is associated with academic decline in mathematics.

Severe small size for gestational age and cognitive function: catch-up phenomenon possible

We sought to compare cognitive functioning in children born with birthweight <3% vs ≥3% for gestational age (GA) between 9 months and kindergarten. Nonanomalous singletons from the Early Childhood Longitudinal Study-Birth Cohort were included. Associations between weight for GA and cognitive functioning were examined using a series of confounder-adjusted general linear models. Of 3633 cohorts, 585 (16%) were <3% for GA. At 9 months, cognitive performance of newborns <3% was about 12 percentile points lower than their normal counterparts (P < .001). By 2 years, however, no significant cognitive differences between these groups were observed (P = .668). Academic performance at preschool age (around 3.5 years) was not different for reading (P = .245) or math (P = .880), nor different at kindergarten age. Newborns <3% for GA exhibit catch-up cognitive functioning by 2 years, with relatively no decrements in academic functioning observed by kindergarten.

Should measures of patient experience in primary care be adjusted for case mix? Evidence from the English General Practice Patient Survey

ObjectivesUncertainties exist about when and how best to adjust performance measures for case mix. Our aims are to quantify the impact of case-mix adjustment on practice-level scores in a national...

Corporations and local economies in the Brazilian Amazon: the impacts of the mining sectors scheduled investments in Southeastern Pará (2004–2010)

Southeastern Pará is an extraordinarily dynamic region. There were large cattle ranching projects, financed in the 1960s. Expansion of peasant agriculture, mineral projects and gold prospecting followed the ranching projects. Also important structural transformations reinforced the role of the urban centres and the local rural bases in the logistics of new economic sectors conditioned by the presence of Companhia Vale do Rio Doce (CVRD), in the region since 1985. This article presents the results of an input–output analysis of the investment programme of CVRD from year 2004 up to 2010. The main findings are that the mineral sector has achieved a considerable influence over the economy of Southeastern Pará, so that during the cycle of investments each 1% in the growth of the mineral production creates growth possibilities of about 0.83% for the agricultural sector and about 0.86% for the local urban sectors. Considering just the production growth, a percentile point will imply growth at, respectively, 0.73% and 0.76% for those sectors. For the economy of the rest of the state of Pará, those elasticities would be, incorporating the investments, 0.80% and, without them, 0.68%. For the economy of the rest of Brazil they would be, respectively, 0.88% and 0.78%.

Development of reference equations for spirometry in japanese children aged 6–18 years

Spirometry is the most widely used pulmonary function test and the measured values of spirometric parameters need to be evaluated using reference values predicted for the corresponding race, sex, age, and height. However, none of the existing reference equations for Japanese children covers the entire age range of 6-18 years. The Japanese Society of Pediatric Pulmonology had organized a working group in 2006, in order to develop a new set of national standard reference equations for commonly used spirometric parameters that are applicable through the age range of 6-18 years. Quality assured spirometric data were collected through 2006-2008, from 14 institutions in Japan. We applied multiple regression analysis, using age in years (A), square of age (A(2)), height in meters (H), square of height (H(2)), and the product of age and height (AH) as explanatory variables to predict forced vital capacity (FVC), forced expiratory volume in 1 sec (FEV(1)), peak expiratory flow (PEF), forced expiratory flow between 25% and 75% of the FVC (FEF(25-75%)), instantaneous forced expiratory flow when 50% (FEF(50%)) or 75% (FEF(75%)) of the FVC have been expired. Finally, 1,296 tests (674 boys, 622 girls) formed the reference data set. Distributions of the percent predicted values did not differ by ages, confirming excellent fit of the prediction equations throughout the entire age range from 6 to 18 years. Cut-off values (around 5 percentile points) for the parameters were also determined. We recommend the use of this new set of prediction equations together with suggested cut-off values, for assessment of spirometry in Japanese children and adolescents.

Randomised controlled trial for emphysema with a selective agonist of the γ-type retinoic acid receptor

Palovarotene is an oral γ-selective retinoid agonist. In animal emphysema models, palovarotene reduced inflammation, promoted structural repair and functional improvement. REPAIR (Retinoid treatment of Emphysema in Patients on the α(1)-antitrypsin International Registry), was an investigator-initiated, double-blind, placebo-controlled randomised study to assess the safety and efficacy of 5 mg·day(-1) palovarotene given for 1 year to 262 patients with severe α(1)-antitrypsin deficiency and emphysema confirmed by computed tomography. Change in volume-adjusted 15th percentile point lung density from baseline in 1 year was the primary end-point; functional end-points were also regularly assessed. We randomly assigned 133 and 129 patients to placebo or palovarotene, respectively. Both groups were well matched for all baseline characteristics, including respiratory medications. 88% and 85% of patients completed 1 year of treatment with placebo and palovarotene, respectively. Palovarotene was generally well tolerated. In the study completers population, the placebo-corrected difference of lung density was -0.45 HU at week 28 (p=0.64) and -0.25 HU at week 52 (p=0.94). A nonsignificant treatment difference in most functional parameters of the lung in favour of the drug was observed over time suggesting potential pharmacological effects of palovarotene. Palovarotene 5 mg·day(-1) over 1 yr failed to show a significant benefit on lung density in moderate-to-severe emphysema secondary to severe α(1)-antitrypsin deficiency.

Asymptotic Expansion of the Percentiles for a Sample Mean Standardized by GMD in a Normal Case with Applications

This paper develops an asymptotic expansion of a percentile point of the Ginibased standardized sample mean. Such approximate percentiles can be used for proposing tests of hypotheses or confidence intervals of μ when samples arrive from a normal distribution with unknown mean μ and standard deviation σ. We have asymptotically expressed the percentile point bm,α of the Gini-based pivot (1.5), that is, the Gini-based standardized sample mean. Using large-scale simulations, approximations, and data analyses, we report that the Gini-based test and confidence interval procedures for μ perform better or practically as well as the customarily employed Student’s t-based procedures when samples arrive from a normal distribution with suspect outliers. This interesting finding is especially noteworthy when we have a small random sample from a normal population with possible outliers.

The Novelty Paradox &amp; Bias for Normal Science: Evidence from Randomized Medical Grant Proposal Evaluations

Central to any innovation process is the evaluation of proposed projects and allocation of resources. We investigate whether novel research projects, those deviating from existing research paradigms, are treated with a negative bias in expert evaluations. We analyze the results of a peer review process for medical research grant proposals at a leading medical research university, in which we recruited 142 expert university faculty members to evaluate 150 submissions, resulting in 2,130 randomly-assigned proposal-evaluator pair observations. Our results confirm a systematic penalty for novel proposals; a standard deviation increase in novelty drops the expected rank of a proposal by 4.5 percentile points. This discounting is robust to various controls for unobserved proposal quality and alternative explanations. Additional tests suggest information effects rather than strategic effects account for the novelty penalty. Only a minority of the novelty penalty could be related to perceptions of lesser feasibility of novel proposals.

A volatilidade de projetos industriais para uso em análise de risco de investimentos

A volatilidade em projetos industriais é um parâmetro significativo na análise de risco de investimentos. Quando se avaliam ativos financeiros, a volatilidade pode ser determinada por meio de dados históricos do ativo, porém, ao se trabalhar com projetos industriais, normalmente, não existem dados históricos. Este fato torna a volatilidade um parâmetro crítico de ser determinado. Este artigo faz a aplicação e a comparação de três abordagens para determinação da volatilidade de um projeto de uma indústria de transformação. Duas destas abordagens adotadas, a "Abordagem Consolidada da Volatilidade de Copeland e Antikarov (2001)" e a "Estimativa de Volatilidade de Herath e Park (2002)", foram obtidas a partir de uma revisão bibliográfica de métodos para cálculo de volatilidade de projetos de investimentos. A terceira abordagem é uma nova proposta para o cálculo da volatilidade, chamada de "A Estimativa da Volatilidade Através da Dependência entre VPo e VP1" . O trabalho realiza a avaliação tradicional de investimentos em um projeto industrial, no qual são aplicadas as três diferentes abordagens de determinação da volatilidade. Conclui-se, com um comparativo entre as três abordagens, que a diferença entre o maior e o menor valor encontrado para a volatilidade é de dezenove pontos percentuais.

Improved regression models for ventilation estimation based on chest and abdomen movements

Non-invasive estimation of minute ventilation is important for quantifying the intensity of physical activity of individuals. In this paper, several improved regression models are presented, based on the measurement of chest and abdomen movements from sensor belts worn by subjects (n = 50) engaged in 14 types of physical activity. Five linear models involving a combination of 11 features were developed, and the effects of different model training approaches and window sizes for computing the features were investigated. The performance of the models was evaluated using experimental data collected during the physical activity protocol. The predicted minute ventilation was compared to the criterion ventilation measured using a bidirectional digital volume transducer housed in a respiratory gas exchange system. The results indicate that the inclusion of breathing frequency and the use of percentile points instead of interdecile ranges over a 60 s window size reduced error by about 43%, when applied to the classical two-degrees-of-freedom model. The mean percentage error of the minute ventilation estimated for all the activities was below 7.5%, verifying reasonably good performance of the models and the applicability of the wearable sensing system for minute ventilation estimation during physical activity.

Erratum to: A Multiple Choice Testing Program Coupled with a Year-long Elective Experience is Associated with Improved Performance on the Internal Medicine In-Training Examination

The Internal Medicine In-Training Exam (IM-ITE) assesses the content knowledge of internal medicine trainees. Many programs use the IM-ITE to counsel residents, to create individual remediation plans, and to make fundamental programmatic and curricular modifications.To assess the association between a multiple-choice testing program administered during 12 consecutive months of ambulatory and inpatient elective experience and IM-ITE percentile scores in third post-graduate year (PGY-3) categorical residents.Retrospective cohort study.One hundred and four categorical internal medicine residents. Forty-five residents in the 2008 and 2009 classes participated in the study group, and the 59 residents in the three classes that preceded the use of the testing program, 2005-2007, served as controls.A comprehensive, elective rotation specific, multiple-choice testing program and a separate board review program, both administered during a continuous long-block elective experience during the twelve months between the second post-graduate year (PGY-2) and PGY-3 in-training examinations.We analyzed the change in median individual percent correct and percentile scores between the PGY-1 and PGY-2 IM-ITE and between the PGY-2 and PGY-3 IM-ITE in both control and study cohorts. For our main outcome measure, we compared the change in median individual percentile rank between the control and study cohorts between the PGY-2 and the PGY-3 IM-ITE testing opportunities.After experiencing the educational intervention, the study group demonstrated a significant increase in median individual IM-ITE percentile score between PGY-2 and PGY-3 examinations of 8.5 percentile points (p < 0.01). This is significantly better than the increase of 1.0 percentile point seen in the control group between its PGY-2 and PGY-3 examination (p < 0.01).A comprehensive multiple-choice testing program aimed at PGY-2 residents during a 12-month continuous long-block elective experience is associated with improved PGY-3 IM-ITE performance.