Estimation of the Coefficient of Variation with Minimum Risk: A Sequential Method for Minimizing Sampling Error and Study Cost

Chattopadhyay, Bhargab; Kelley, Ken

doi:10.1080/00273171.2016.1203279

Cited by 20 publications

(28 citation statements)

References 35 publications

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“…We used SAS (Version 9.3) and SUDAAN (Version 11) procedures, which are appropriate to analyze complex survey data. We considered estimates with a coefficient of variation greater than 0.3 unreliable [23].…”

Section: Methodsmentioning

confidence: 99%

HIV-Related Training and Correlates of Knowledge, HIV Screening and Prescribing of nPEP and PrEP Among Primary Care Providers in Southeast United States, 2017

et al. 2019

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The Southeast accounted for most HIV diagnoses (52%) in the United States in 2015. Primary care providers (PCPs) play a vital role in HIV prevention for at-risk persons and treatment of persons living with HIV. We studied HIV-related training, knowledge, and clinical practices among PCPs in the Southeast to address knowledge gaps to inform HIV prevention strategies. Between April and August 2017, we conducted an on-line survey of a representative sample of PCPs in six Southeast jurisdictions with high rates of HIV diagnoses (Atlanta; Baltimore; Baton Rouge; District of Columbia; Miami; New Orleans). We defined HIV-related training as self-reported completion of any certified HIV/STD course or continuing education in past 24 months (prior to survey completion). We assessed associations between training and HIV testing practices, familiarity with nonoccupational post-exposure prophylaxis (nPEP) and pre-exposure prophylaxis (PrEP), and ever prescribing nPEP or PrEP. There were 820 participants after fielding 4595 surveys (29.6% adjusted response rate). In weighted analyses, 36.3% reported HIV-related training. Using adjusted prevalence ratio (aPR) and confidence intervals (CI), we found that PCPs with HIV-related training (compared to those with no training) were more likely to be familiar with nPEP (aPR = 1.32, 95% CI 1.05, 1.67) and PrEP (aPR = 1.67, 95% CI 1.19, 2.38); and to have ever prescribed PrEP to patients (aPR = 1.75, 95% CI 1.10, 2.78). Increased HIV-related trainings among PCPs in high HIV prevalence Southeast jurisdictions may be warranted. Strengthening nPEP and PrEP familiarity among PCPs in Southeast may advance national HIV prevention goals.

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Section: Methodsmentioning

confidence: 99%

HIV-Related Training and Correlates of Knowledge, HIV Screening and Prescribing of nPEP and PrEP Among Primary Care Providers in Southeast United States, 2017

et al. 2019

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“…They mathematically showed that the proposed procedure a ains asymptotic efficiency and consistency in the sense of Chow and Robbins [25]. Cha opadhyay and Kelley [26] used the purely sequential procedure [25] to estimate the population coefficient of variation of the normal distribution under a squared-error loss function using a Nagar-type expansion.…”

Section: Introductionmentioning

confidence: 99%

Three-Stage Sequential Estimation of the Inverse Coefficient of Variation of the Normal Distribution

Yousef

Hamdy

2019

Computation

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This paper sequentially estimates the inverse coefficient of variation of the normal distribution using Hall’s three-stage procedure. We find theorems that facilitate finding a confidence interval for the inverse coefficient of variation that has pre-determined width and coverage probability. We also discuss the sensitivity of the constructed confidence interval to detect a possible shift in the inverse coefficient of variation. Finally, we find the asymptotic regret encountered in point estimation of the inverse coefficient of variation under the squared-error loss function with linear sampling cost. The asymptotic regret provides negative values, which indicate that the three-stage sampling does better than the optimal fixed sample size had the population inverse coefficient of variation been known.

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“…On the basis of the descriptive statistics and the division of driver’s saccade angle, the coefficient of variation was used to analyze the driver’s saccade characteristics under different alignments and curvature conditions. When the mean values of multiple sets of data were different, the coefficient of variation could reflect the degree of dispersion of the data from the unit mean ( 27 ). The coefficient of variation is given by:…”

Section: Discussion Of Resultsmentioning

confidence: 99%

Drivers’ Saccade Characteristics in Curves of Extra-Long Urban Underwater Tunnels

Jiao

Wang

et al. 2020

Transportation Research Record: Journal of the Transportation R

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Traffic accidents in extra-long urban underwater tunnels are characterized by high numbers of causalities and severe traffic congestion. Analyzing drivers’ saccade characteristics under different curvature conditions in urban underwater tunnels can provide solutions to reduce the rates of such accidents and increase traffic safety. This paper reports real vehicle tests conducted in extra-long urban underwater tunnels, on curved sections of radii of 400, 680, 1,000, 1,500, and 3,000 m, and also on straight sections. Indicators of drivers’ saccade behavior, such as saccade angle, time, and frequency, and the saccade time ratio were evaluated. The coefficient of variation was used to analyze the discreteness of the saccade angle. The driver’s saccade characteristics, such as saccade time and frequency, were explored by combining the visual distances for different curved sections. The results demonstrated that (a) small angles in the range of [0, 10°] constituted the main distribution section of the driver’s saccade angle in extra-long urban underwater tunnels, and the saccade angle discreteness increased with increase in the radius, (b) the driver’s average saccade time increased while the average saccade frequency decreased with the increase of the radius, (c) the driver’s visual load was higher for long straight sections and small-radius curves, (d) the driver’s safety was generally higher on right-curving sections than on left-curving sections.

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Estimation of the Coefficient of Variation with Minimum Risk: A Sequential Method for Minimizing Sampling Error and Study Cost

Cited by 20 publications

References 35 publications

HIV-Related Training and Correlates of Knowledge, HIV Screening and Prescribing of nPEP and PrEP Among Primary Care Providers in Southeast United States, 2017

HIV-Related Training and Correlates of Knowledge, HIV Screening and Prescribing of nPEP and PrEP Among Primary Care Providers in Southeast United States, 2017

Three-Stage Sequential Estimation of the Inverse Coefficient of Variation of the Normal Distribution

Drivers’ Saccade Characteristics in Curves of Extra-Long Urban Underwater Tunnels

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