scholarly journals Handling Missing Entries in Monitoring a Woman’s Monthly Cycle and Controlling Fertility

2018 ◽  
Vol 56 (1) ◽  
pp. 75-90
Author(s):  
Anna Łupińska-Dubicka
Keyword(s):  
Statistical Power ◽  
Dynamic Bayesian Network ◽  
Missing Observations ◽  
Fertility Awareness ◽  
Average Percentage ◽  
Fertile Window ◽  
Bayesian Network Modeling ◽  
Two Measures ◽  
Monthly Cycle

Abstract Even a small percentage of missing data can cause serious problems with analysis, reducing the statistical power of a study and leading to wrong conclusions being drawn. In the case of monitoring a woman’s monthly cycle, missing entries can appear even in a woman experienced in fertility awareness methods. Due to the fact that in a system of controlling a woman’s fertility, it is the most important to predict the day of ovulation and, ultimately, to determine the fertile window as much precisely as possible, much attention should be paid to the quality of the used data. This paper presents the results of handling missing observations as far as predicting the time during the cycle when a woman can become pregnant is concerned. Data taken from a multinational European study of daily fecundability was used to learn the quantitative part of the variety of a higher-order dynamic Bayesian network modeling a woman’s monthly cycle. The main goal of this paper is to examine whether omitting observations has an influence on the model’s reliability. The accuracy of comparison was examined based on two measures: the average percentage length of the infertile time during the monthly cycle and average percentage of days inside the fertile window classified as infertile.

scholarly journals Ordinal outcome analysis improves the detection of between-hospital differences in outcome

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
I. E. Ceyisakar ◽  
N. van Leeuwen ◽  
Diederik W. J. Dippel ◽  
Ewout W. Steyerberg ◽  
H. F. Lingsma
Keyword(s):  
Logistic Regression ◽  
Quality Of Care ◽  
Outcome Measures ◽  
Statistical Power ◽  
Ordinal Scale ◽  
Efficiency Gain ◽  
Number Of Patients ◽  
Dichotomous Outcomes ◽  
Ordinal Outcome

Abstract Background There is a growing interest in assessment of the quality of hospital care, based on outcome measures. Many quality of care comparisons rely on binary outcomes, for example mortality rates. Due to low numbers, the observed differences in outcome are partly subject to chance. We aimed to quantify the gain in efficiency by ordinal instead of binary outcome analyses for hospital comparisons. We analyzed patients with traumatic brain injury (TBI) and stroke as examples. Methods We sampled patients from two trials. We simulated ordinal and dichotomous outcomes based on the modified Rankin Scale (stroke) and Glasgow Outcome Scale (TBI) in scenarios with and without true differences between hospitals in outcome. The potential efficiency gain of ordinal outcomes, analyzed with ordinal logistic regression, compared to dichotomous outcomes, analyzed with binary logistic regression was expressed as the possible reduction in sample size while keeping the same statistical power to detect outliers. Results In the IMPACT study (9578 patients in 265 hospitals, mean number of patients per hospital = 36), the analysis of the ordinal scale rather than the dichotomized scale (‘unfavorable outcome’), allowed for up to 32% less patients in the analysis without a loss of power. In the PRACTISE trial (1657 patients in 12 hospitals, mean number of patients per hospital = 138), ordinal analysis allowed for 13% less patients. Compared to mortality, ordinal outcome analyses allowed for up to 37 to 63% less patients. Conclusions Ordinal analyses provide the statistical power of substantially larger studies which have been analyzed with dichotomization of endpoints. We advise to exploit ordinal outcome measures for hospital comparisons, in order to increase efficiency in quality of care measurements. Trial registration We do not report the results of a health care intervention.

Robust Trimming of Automotive Panels

2007 ◽  
Vol 539-543 ◽  
pp. 423-428 ◽  
Author(s):  
S.F. Golovashchenko
Keyword(s):  
Crack Propagation ◽  
Elastic Support ◽  
Small Radius ◽  
Automotive Body ◽  
Two Measures ◽  
Trimmed Surface ◽  
Automotive Panels ◽  
Exterior Panel

Small pieces of metal are generated during trimming of automotive body panels. Commonly referred to as slivers, these pieces can be imprinted into the surface of stamped panels. This may require metalfinish of every stamped exterior panel. The objective of the paper is to study the influence of trimming conditions on quality of trimmed surface and to modify the trimming process to eliminate slivers and burrs from the trimmed surface. Suggested solution includes two measures: 1) building an elastic support of the offal eliminating bending of the area of the blank being trimmed off; 2) creating the preference of crack propagation from the lower shearing edge by machining a small radius on the upper shearing edge.

scholarly journals REPRODUCING QUALITIES OF RAMS OF THE MOLDOVAN TYPE KARAKUL BREED

2020 ◽  
Vol 59 ◽  
pp. 92-96
Author(s):  
D. Rotari
Keyword(s):  
Sperm Count ◽  
Sperm Concentration ◽  
Animal Husbandry ◽  
Sperm Production ◽  
Livestock Farming ◽  
High Quality ◽  
Average Percentage ◽  
Reproductive Ability ◽  
First Time

Issues related to the reproduction of animals have been and remain one of the most complex and relevant problems of biology and are constantly finding a direct and effective way out into livestock farming practice. The rational use of breeding sheep as producers is limited by the lack of standard, objective methods and methods for the timely assessment of their reproductive ability. The article presents the results of evaluating the sperm production of rams-producers. For the first time, the freshly obtained sperm of rams of Moldavian type producers of the Karakul breed was evaluated using the macroscopic method - ejaculate volume, color and smell, as well as the microscopic method - motility, sperm concentration in the ejaculate, total sperm count in the ejaculate sperm movements (VAP; VSL and VCL) as well as the percentage of abnormal forms of sperm. The experiments were carried out on sheep producers grown on a pedigree farm of the experimental farm of the Moldavian Scientific and Practical Institute of Biotechnology in Animal Husbandry and Veterinary Medicine. As a result of the studies, it was found that the ejaculate volume on average was 0.99 ± 0.04 ml, motility was 0.95 ± 0.02 and sperm concentration 1.51 ± 0.14 billion/ml. The percentage of pathological forms in sperm averaged 13.72 ± 0.61, an indicator that characterizes the high quality of sperm. The average quality indicator of ejaculates obtained from ram-producers of the Moldavian type of the Karakul breed corresponds to physiological standards for the Karakul breed. The average percentage of pathological forms of sperm found in ejaculates indicates that the rams were in good conditions of feeding and keeping. According to research, we can say that the Moldovan type of Karakul rams can be successfully used to obtain high quality ejaculates suitable for freezing sperm at 196°C.

scholarly journals Physical design development for evaluate digital library application based on modified CSE-UCLA with weighted product

2018 ◽  
Vol 197 ◽  
pp. 15003
Author(s):  
Dewa Gede Hendra Divayana ◽  
P. Wayan Arta Suyasa ◽  
Ida Bagus Gede Surya Abadi
Keyword(s):  
Digital Library ◽  
Physical Design ◽  
Trial Result ◽  
Library Services ◽  
Design Development ◽  
Average Percentage ◽  
Analysis Technique ◽  
Digital Library Services ◽  
Library Evaluation

Digital library as one of the supporting services of information technology-based learning process has been found in many universities, but in the implementation, there are still many obstacles. Therefore, it is necessary to evaluate using appropriate tools to obtain accurate results. Based on that, the primary purpose of this paper is to explain the physical design of applications that apply the modified CSE-UCLA model with weighted product method, so it can be used to evaluate the digital library. Subjects involved in conducting trials on this application for digital library evaluation are four peoples consisting of two educational experts and two informatics experts. The location of the experiment was done in one of the computer universities in Bali Province. The tool used to collect data of trial result is in the form of questionnaires. The analysis technique used is descriptive quantitative concerning the quality percentage of each trial aspects. The results obtained from this study were average percentage of evaluation application quality of 92.00% belonging to the excellent category, so it can be concluded in general that applications were ready for use to evaluate the quality of digital library services.

scholarly journals QUALIDADE AMBIENTAL DA ÁGUA SUPERFICIAL DO CÓRREGO QUATRO VINTÉNS NO MUNICÍPIO DE DIAMANTINA-MG

2020 ◽  
Vol 14 (01) ◽  
pp. 77-95
Author(s):  
Amanda Dias Araujo ◽  
Mariana de Oliveira Freitas ◽  
Hernando Baggio Filho
Keyword(s):  
Water Samples ◽  
Urban Areas ◽  
Environmental Geochemistry ◽  
Palabras Clave ◽  
Two Measures ◽  
Del Rio ◽  
Intensive Land Use ◽  
The City ◽  
Dry And Rainy Seasons

O Córrego Quatro Vinténs faz parte da bacia hidrográfica do rio Jequitinhonha, localizado no município de Diamantina-MG. Neste trabalho avaliou-se a qualidade ambiental das águas superficiais deste córrego por meio da medição de dois parâmetros físico-químicos cor da água e turbidez. Com o recolhimento de amostras ao longo do canal do córrego foi possível relacionar os impactos aos ambientes naturais e às interferências antropogênicas, englobando as características geoambientais da área. Foram amostrados 12 pontos considerando a variação sazonal em duas campanhas de amostragem (nas estações seca e chuvosa), totalizando 24 amostras de água. As amostras foram analisadas no Laboratório de Geoquímica Ambiental – LGA/UFVJM e os resultados comparados com os valores estabelecidos pela Resolução CONAMA 357/05 e Portaria do Ministério da Saúde N° 2.914/2011. Os valores de turbidez (UNT) e cor da água (mg/L), tanto numa estação quanto noutra se apresentaram elevados, haja vista que a área está totalmente inserida em locais de uso intensivo do solo e áreas urbanas. Palavras-chave: Geoquímica Ambiental; Córrego Quatro Vinténs; Serra do Espinhaço Meridional.   ENVIRONMENTAL QUALITY STREAM OF SURFACE WATER IN QUATRO VINTÉNS DIAMANTINA MUNICIPALITY – MG Abstract The Quatro Vintens stream part of the basin of the Jequitinhonha River, which is located in the city of Diamantina. The aim of this work is to evaluate the environmental geochemistry quality of superficial waters of this stream through two measures physical-chemical parameters water color and turbidity. Collecting samples along the stream channel was possible to relate to natural and anthropogenic interference environments, encompassing geo-environmental characteristics of the area. 12 points were sampled considering the seasonal variation in two sampling campaigns (in the dry and rainy seasons), totaling 24 water samples. Water samples were analyzed in the Environmental Geochemistry Laboratory - LGA/UFVJM and the results compared to the values ​​established by CONAMA Resolution 357/05 and Ordinance of the Ministry of Health N°. 2.914/2011. The turbidity values ​​(UNT) and color of the water (mg/L), both at a station in another as the values ​​presented high, given that the area is fully inserted in places of intensive land use and urban areas. Keywords: Environmental Geochemistry; Quatro Vinténs Stream; Diamantina; Espinhaço Meridional Ranger.   CALIDAD AMBIENTAL SECUENCIA DEL AGUA DE SUPERFICIE EN QUATRO VINTÉNS DIAMANTINA – MG Resumen La corriente Quatro Vinténs es parte de la cuenca del río Jequitinhonha, que se encuentra en la ciudad de Diamantina-MG. En este trabajo se evaluó la calidad ambiental de las aguas superficiales de esta corriente mediante la medición de dos parámetros físico-químicos del color de agua y turbidez. Con la toma de muestras a lo largo del canal de flujo fue posible relacionar los impactos en el medio ambiente natural y la interferencia antropogénica que abarca las características geo-ambientales de la zona. 12 puntos fueron muestreados teniendo en cuenta la variación estacional en dos campañas de muestreo (en las estaciones seca y lluviosa), un total de 24 muestras de agua. Las muestras fueron analizadas en el Laboratorio de Geoquímica Ambiental - LGA/UFVJM y los resultados en comparación con los valores establecidos por la Resolución CONAMA 357/05 y Decreto del Ministerio de Salud N° 2.914/2011. Los valores de turbidez (NTU) y color del agua (mg/L), tanto como una estación en otro presentan alta, teniendo en cuenta que la zona esté completamente insertado en el uso local de la tierra intensivo y áreas urbanas. Palabras-clave: Geoquímica Ambiental; Codificar Quatro Vinténs; Serra do Espinhaço.

Auctioning IT Contracts with Renegotiable Scope

2021 ◽  
Author(s):  
He Huang ◽  
Zhipeng Li ◽  
De Liu ◽  
Hongyan Xu
Keyword(s):  
Bargaining Power ◽  
It Outsourcing ◽  
Quality Uncertainty ◽  
Strategic Substitutes ◽  
Fixed Price ◽  
Ex Post ◽  
Information Rent ◽  
High Investment ◽  
Two Measures

Motivated by challenges facing IT procurement, this paper studies a hybrid procurement model in which a reverse auction of a fixed-price IT outsourcing contract may be followed by renegotiation to extend the contract’s scope. In this model, the buyer balances the needs to incentivize noncontractible vendor investment and to curb the winning vendor’s information rent by choosing the initial project scope and the buyer’s investment in the quality of the project. We find that a buyer may benefit from inducing ex post renegotiation to motivate vendor investment, especially when the winning vendor has high bargaining power and the quality uncertainty is low. Broadening the initial scope reduces information rent but leaves little room for ex post renegotiation and, hence, discourages vendor investment, whereas increasing the buyer’s investment has opposite effects. Interestingly, the two measures can be strategic substitutes or complements depending on the likelihood of the renegotiation and the two parties’ bargaining powers. The buyer may strategically set a low initial project scope and high investment to incentivize renegotiation and vendor investment, which may explain why many IT outsourcing projects start small and allow expansions. Our findings also generate several testable predictions for IT outsourcing. This paper was accepted by Kartik Hosanagar, information systems.

The win ratio approach for composite endpoints: practical guidance based on previous experience

2020 ◽  
Vol 41 (46) ◽  
pp. 4391-4399 ◽  
Author(s):  
Björn Redfors ◽  
John Gregson ◽  
Aaron Crowley ◽  
Thomas McAndrew ◽  
Ori Ben-Yehuda ◽  
...  
Keyword(s):  
Statistical Power ◽  
Fatal Outcome ◽  
Composite Endpoint ◽  
Exercise Tests ◽  
Time To Death ◽  
Ratio Approach ◽  
Practical Guidance ◽  
Composite Endpoints ◽  
Available Information

Abstract The win ratio was introduced in 2012 as a new method for examining composite endpoints and has since been widely adopted in cardiovascular (CV) trials. Improving upon conventional methods for analysing composite endpoints, the win ratio accounts for relative priorities of the components and allows the components to be different types of outcomes. For example, the win ratio can combine the time to death with the number of occurrences of a non-fatal outcome such as CV-related hospitalizations (CVHs) in a single hierarchical composite endpoint. The win ratio can provide greater statistical power to detect and quantify a treatment difference by using all available information contained in the component outcomes. The win ratio can also incorporate quantitative outcomes such as exercise tests or quality-of-life scores. There is a need for more practical guidance on how best to design trials using the win ratio approach. This manuscript provides an overview of the principles behind the win ratio and provides insights into how to implement the win ratio in CV trial design and reporting, including how to determine trial size.

scholarly journals Core–periphery structure in directed networks

2020 ◽  
Vol 476 (2241) ◽  
pp. 20190783
Author(s):  
Andrew Elliott ◽  
Angus Chiu ◽  
Marya Bazzi ◽  
Gesine Reinert ◽  
Mihai Cucuringu
Keyword(s):  
Statistical Significance ◽  
Ground Truth ◽  
Directed Networks ◽  
Political Blogs ◽  
Novel Structure ◽  
Two Measures ◽  
Likelihood Approach ◽  
Core Sets ◽  
Empirical Networks

Empirical networks often exhibit different meso-scale structures, such as community and core–periphery structures. Core–periphery structure typically consists of a well-connected core and a periphery that is well connected to the core but sparsely connected internally. Most core–periphery studies focus on undirected networks. We propose a generalization of core–periphery structure to directed networks. Our approach yields a family of core–periphery block model formulations in which, contrary to many existing approaches, core and periphery sets are edge-direction dependent. We focus on a particular structure consisting of two core sets and two periphery sets, which we motivate empirically. We propose two measures to assess the statistical significance and quality of our novel structure in empirical data, where one often has no ground truth. To detect core–periphery structure in directed networks, we propose three methods adapted from two approaches in the literature, each with a different trade-off between computational complexity and accuracy. We assess the methods on benchmark networks where our methods match or outperform standard methods from the literature, with a likelihood approach achieving the highest accuracy. Applying our methods to three empirical networks—faculty hiring, a world trade dataset and political blogs—illustrates that our proposed structure provides novel insights in empirical networks.

scholarly journals Quality of Daily-Life Gait: Novel Outcome for Trials that Focus on Balance, Mobility, and Falls

Sensors ◽  
2019 ◽  
Vol 19 (20) ◽  
pp. 4388 ◽  
Author(s):  
Kimberley S. van Schooten ◽  
Mirjam Pijnappels ◽  
Stephen R. Lord ◽  
Jaap H. van Dieën
Keyword(s):  
Fall Risk ◽  
Statistical Power ◽  
Inertial Sensors ◽  
Daily Life ◽  
Gait Characteristics ◽  
Technological Advances ◽  
Gait Quality ◽  
Intervention Trials ◽  
Variance Estimates

Technological advances in inertial sensors allow for monitoring of daily-life gait characteristics as a proxy for fall risk. The quality of daily-life gait could serve as a valuable outcome for intervention trials, but the uptake of these measures relies on their power to detect relevant changes in fall risk. We collected daily-life gait characteristics in 163 older people (aged 77.5 ± 7.5, 107♀) over two measurement weeks that were two weeks apart. We present variance estimates of daily-life gait characteristics that are sensitive to fall risk and estimate the number of participants required to obtain sufficient statistical power for repeated comparisons. The provided data allows for power analyses for studies using daily-life gait quality as outcome. Our results show that the number of participants required (i.e., 8 to 343 depending on the anticipated effect size and between-measurements correlation) is similar to that generally used in fall prevention trials. We propose that the quality of daily-life gait is a promising outcome for intervention studies that focus on improving balance and mobility and reducing falls.

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