scholarly journals COVID-19 prevalence estimation by random sampling in the population - Optimal sample pooling under varying assumptions about true prevalence

2020 ◽  
Author(s):  
Ola Brynildsrud
Keyword(s):  
Random Sampling ◽  
Large Fraction ◽  
Positive Sample ◽  
Individual Level ◽  
True Prevalence ◽  
Prevalence Estimation ◽  
Optimal Sample ◽  
Sample Pooling ◽  
Many Sources ◽  
The Cost

Abstract Background The number of confirmed COVID-19 cases divided by population size is used as a coarse measurement for the burden of disease in a population. However, this fraction depends heavily on the sampling intensity and the various test criteria used in different jurisdictions, and many sources indicate that a large fraction of cases tend to go undetected. Methods Estimates of the true prevalence of COVID-19 in a population can be made by random sampling. Here I use simulations to explore confidence intervals of prevalence estimates under different sampling strategies, exploring optimal sample sizes and degrees of sample pooling at a range of true prevalence levels. Results Sample pooling can greatly reduce the total number of tests required for prevalence estimation. In low-prevalence populations, it is theoretically possible to pool hundreds of samples with only marginal loss of precision. Even when the true prevalence is as high as 10% it can be appropriate to pool up to 15 samples, although this comes with the cost of not knowing which patients were positive. Sample pooling can be particularly beneficial when the test has imperfect specificity can provide more accurate estimates of the prevalence than an equal number of individual-level tests. Conclusion Sample pooling should be considered in COVID-19 prevalence estimation efforts.

scholarly journals COVID-19 prevalence estimation by random sampling in population - Optimal sample pooling under varying assumptions about true prevalence

2020 ◽  
Author(s):  
Ola Brynildsrud
Keyword(s):  
Random Sampling ◽  
Large Fraction ◽  
Rt Pcr ◽  
Individual Level ◽  
True Prevalence ◽  
Prevalence Estimation ◽  
Prevalence Estimates ◽  
Sample Pooling ◽  
Many Sources ◽  
Low Prevalence

Abstract Background: The number of confirmed COVID-19 cases divided by population size is used as a coarse measurement for the burden of disease in a population. However, this fraction depends heavily on the sampling intensity and the various test criteria used in different jurisdictions, and many sources indicate that a large fraction of cases tend to go undetected. Methods: Estimates of the true prevalence of COVID-19 in a population can be made by random sampling and pooling of RT-PCR tests. Here I use simulations to explore how experiment sample size and degrees of sample pooling impact precision of prevalence estimates and potential for minimizing the total number of tests required to get individual-level diagnostic results.Results: Sample pooling can greatly reduce the total number of tests required for prevalence estimation. In low-prevalence populations, it is theoretically possible to pool hundreds of samples with only marginal loss of precision. Even when the true prevalence is as high as 10% it can be appropriate to pool up to 15 samples. Sample pooling can be particularly beneficial when the test has imperfect specificity by providing more accurate estimates of the prevalence than an equal number of individual-level tests.Conclusion: Sample pooling should be considered in COVID-19 prevalence estimation efforts.

scholarly journals Covid-19 prevalence estimation by random sampling in the wider population - Optimal sample pooling under varying assumptions about true prevalence

2020 ◽  
Author(s):  
Ola Brynildsrud
Keyword(s):  
Confidence Intervals ◽  
Random Sampling ◽  
Large Fraction ◽  
True Prevalence ◽  
Prevalence Estimation ◽  
Optimal Sample ◽  
Wide Range ◽  
Prevalence Estimates ◽  
Test Criteria ◽  
Sample Pooling

ABSTRACTThe number of confirmed Covid-19 cases in a population is used as a coarse measurement for the burden of disease. However, this number depends heavily on the sampling intensity and the various test criteria used in different jurisdictions. A wide range of sources indicate that a large fraction of cases go undetected. Estimates of the true prevalence of Covid-19 can be made by random sampling in the wider population. Here we use simulations to explore confidence intervals of prevalence estimates under different sampling intensities and degrees of sample pooling.

Building Illness in the White-Collar Workplace

1983 ◽  
Vol 13 (2) ◽  
pp. 277-287 ◽  
Author(s):  
Theodor D. Sterling ◽  
Elia Sterling ◽  
Helen Dimich-Ward
Keyword(s):  
White Collar ◽  
Respiratory Illnesses ◽  
Mechanically Ventilated ◽  
Pollution Levels ◽  
White Collar Workers ◽  
Many Sources ◽  
The Cost ◽  
Private Homes ◽  
Toxic Fumes ◽  
The Impact

An increasing incidence of “building illness” is being noted among white-collar workers due to the high pollutant content of air in modern energy-efficient office buildings. These buildings are hermetically sealed, mechanically ventilated, and contain many materials that give off a variety of toxic fumes and aerosols. Severe outbreaks of illness have also been traced to ventilation problems in sealed hospital buildings. Similarly, tightly sealed and well insulated private homes present many sources of toxic pollutants to homemakers. Recent studies linking increases in the frequency and duration of respiratory illnesses with increasing pollution levels warn us that increases in indoor pollution levels should be avoided in the white-collar workplace, hospital, and private residence. Unfortunately, the cost of adequate ventilation of modern air-tight buildings is high. However, proper planning must be conducted to foresee and correct the impact of energy management policies on the livability and healthfulness of the indoor environment.

Solar Concentrating Systems Using Small Mirror Arrays

2009 ◽  
Vol 132 (1) ◽  
Author(s):  
Joachim Göttsche ◽  
Bernhard Hoffschmidt ◽  
Stefan Schmitz ◽  
Markus Sauerborn ◽  
Reiner Buck ◽  
...  
Keyword(s):  
Power Plants ◽  
Raw Materials ◽  
Large Fraction ◽  
Steel Structure ◽  
Steel Structures ◽  
Cost Effective ◽  
Wind Loads ◽  
Drive Systems ◽  
Mirror Area ◽  
The Cost

The cost of solar tower power plants is dominated by the heliostat field making up roughly 50% of investment costs. Classical heliostat design is dominated by mirrors brought into position by steel structures and drives that guarantee high accuracies under wind loads and thermal stress situations. A large fraction of costs is caused by the stiffness requirements of the steel structure, typically resulting in ∼20 kg/m2 steel per mirror area. The typical cost figure of heliostats (figure mentioned by Solucar at Solar Paces Conference, Seville, 2006) is currently in the area of 150 €/m2 caused by the increasing price of the necessary raw materials. An interesting option to reduce costs lies in a heliostat design where all moving parts are protected from wind loads. In this way, drives and mechanical layout may be kept less robust, thereby reducing material input and costs. In order to keep the heliostat at an appropriate size, small mirrors (around 10×10 cm2) have to be used, which are placed in a box with a transparent cover. Innovative drive systems are developed in order to obtain a cost-effective design. A 0.5×0.5 m2 demonstration unit will be constructed. Tests of the unit are carried out with a high-precision artificial sun unit that imitates the sun’s path with an accuracy of less than 0.5 mrad and creates a beam of parallel light with a divergence of less than 4 mrad.

scholarly journals Analysis of Effects of Service Quality and Loyalty on Interest Rates of Basketball Athletes in Sahabat Basketball Club Yogyakarta

2020 ◽  
Vol 11 (2) ◽  
pp. 151-160
Author(s):  
Kukuh Hardopo Putro ◽  
Mohd Salleh Aman ◽  
Keyword(s):  
Interest Rates ◽  
Random Sampling ◽  
External Factors ◽  
Major Influence ◽  
Qualitative And Quantitative ◽  
Analysis Techniques ◽  
Using Data ◽  
Internal And External Factors ◽  
The Cost ◽  
Customer Trust

AbstractIn business, especially basketball experience an increased very rapidly, both in terms of quality and quantity in Yogyakarta. Customer as the facilities and services the user pays the cost, much influenced by several internal and external factors. These factors have a major influence on the process of the customer to pay a fee to join and dues in Basketball Clubs. This type of research is descriptive with mixed qualitative and quantitative approach, population in this study is the Athlete Club Basketball “Sahabat” of Yogyakarta, with the number of 20 people, the study sample was determined by random sampling. The technique of collecting data using questionnaires. SPSS.21 using data analysis techniques. While looking at the level of loyalty of respondents to the basketball club Yogyakarta “Sahabat”, 13 of 20 respondents said well (65%) and 7 respondents (35%) had middle loyalty. So from this study showed that customer trust is strongly influenced by the good facilities, appropriate tariffs, staff were nice, the service was very good, and therefore in this study obtained very significant results to customer satisfaction or athletes in the Club Basketball “Sahabat” of Yogyakarta.

The Impact of Military Spending on Economic Development

2018 ◽  
pp. 182-191
Author(s):  
Saptarshi Chakraborty
Keyword(s):  
Economic Growth ◽  
Causal Effect ◽  
Large Fraction ◽  
Military Spending ◽  
Military Expenditure ◽  
Policy Debate ◽  
External Threats ◽  
The Cost ◽  
The Military ◽  
The Impact

Some countries spend a relatively large percentage of GDP on their militaries in order to preserve or secure their status as global powers. Others do so because they are ruled by military governments or aggressive regimes that pose a military threat to their neighbors or their own populations. It is debatable whether there is a causal relationship between military spending and economic growth in the economy. It is again a policy debate how much to allocate funds for civilian and how much for military expenditure. Under these puzzling results of the impact of military expenditure on economic growth which is frequently found to be non-significant or negative, yet most countries spend a large fraction of their GDP on defense and the military. The chapter tries to investigate the relationship between military spending and economic growth in India. It also sees whether external threats, corruption, and other relevant controls have any causal effect. This chapter obtains that additional expenditure on Indian military in the presence of additional threat is significantly detrimental to growth implying that India cannot afford to fight or demonstrate power at the cost of its development.

scholarly journals Automation, Occupational Earnings Trends, and the Moderating Role of Organized Labor

Social Forces ◽  
2020 ◽  
Author(s):  
Zachary Parolin
Keyword(s):  
United States ◽  
The United States ◽  
Social Consequences ◽  
Organized Labor ◽  
Earnings Growth ◽  
Individual Level ◽  
Union Coverage ◽  
Level Data ◽  
Earnings Trends ◽  
The Cost

Abstract Routine-biased technological change has emerged as the dominant explanation for the differential earnings growth of occupations at greater risk of automation, such as machine operators or office clerks, relative to less routine occupations. In contrast, this paper finds that the declining earnings returns to an occupation’s routine task intensity (RTI) can largely be attributed to the decline of organized labor. Using individual-level data on 3.3 million employed adults across the United States from 1983 to 2017, this paper finds that organized labor has two countervailing effects on occupations at greater risk of automation. First, higher union coverage within a state and industry inhibits the decline in earnings returns to an occupation’s RTI. Second, higher union coverage hastens the decline in employment shares of occupations with higher RTI. The result is that occupations at greater risk of automation experience more favorable earnings growth where unions are more resilient, but at the cost of accelerated declines in their employment shares. Counterfactual analyses demonstrate that if union coverage in the United States had remained stable at 1983 levels, the earnings returns to an occupation’s RTI might not have declined from 1983 to 2017, and the observed pattern of occupational earnings polarization in the 1990s might not have occurred. However, the mean RTI of occupations might have declined by an additional 21 percent from 1983 to 2017 relative to the observed decline. The findings suggest that the social consequences of automation are conditional on the strength of organized labor.

scholarly journals The Determination of Sample Size for Sensitive Issue Successive Survey with the Multiplication RRT Model under Two-Stage and Stratified Two-Stage Random Sampling and Its Application in Medical Survey

2019 ◽  
Vol 2019 ◽  
pp. 1-10
Author(s):  
Bo Yu ◽  
Xiaonan Liang ◽  
Ying Wang ◽  
Yun Liu ◽  
Qiao Chang ◽  
...  
Keyword(s):  
Sample Size ◽  
Sampling Method ◽  
Sampling Errors ◽  
Two Stage ◽  
Successive Sampling ◽  
Optimal Sample ◽  
Sensitive Issue ◽  
Survey Accuracy ◽  
The Cost

When designing the sample scheme, it is important to determine the sample size. The survey accuracy and cost of survey and sampling method should be considered comprehensively. In this article, we discuss the method of determining the sample size of complex successive sampling with rotation sample for sensitive issue and deduce the formulas for the optimal sample size under two-stage sampling and stratified two-stage sampling by using Cauchy-Schwartz inequality, respectively, so as to minimize the cost for given sampling errors and to minimize the sampling errors for given cost.

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