scholarly journals Inflated false negative rates undermine reproducibility in task-based fMRI

2017 ◽  
Author(s):  
G. Lohmann ◽  
J. Stelzer ◽  
K. Müller ◽  
E. Lacosse ◽  
T. Buschmann ◽  
...  
Keyword(s):  
False Positive ◽  
False Negative ◽  
Sample Sizes ◽  
Test Statistic ◽  
Scientific Validity ◽  
Full Cohort ◽  
Positive Effects ◽  
Software Packages ◽  
Human Connectome Project

AbstractReproducibility is generally regarded as a hallmark of scientific validity. It can be undermined by two very different factors, namely inflated false positive rates or inflated false negative rates. Here we investigate the role of the second factor, i.e. the degree to which true effects are not detected reliably. The availability of large public databases and also supercomputing allows us to tackle this problem quantitatively. Specifically, we estimated the reproducibility in task-based fMRI data over different samples randomly drawn from a large cohort of subjects obtained from the Human Connectome Project. We use the full cohort as a standard of reference to approximate true positive effects, and compute the fraction of those effects that was detected reliably using standard software packages at various smaller sample sizes. We found that with standard sample sizes this fraction was less than 25 percent. We conclude that inflated false negative rates are a major factor that undermine reproducibility. We introduce a new statistical inference algorithm based on a novel test statistic and show that it improves reproducibility without inflating false positive rates.

scholarly journals Role of Hysterosalpingography for Evaluation of Infertility

1970 ◽  
Vol 39 (1) ◽  
pp. 16-23 ◽  
Author(s):  
Shahara Haque
Keyword(s):  
Medical Journal ◽  
Diagnostic Tool ◽  
False Positive ◽  
False Negative ◽  
Uterine Cavity ◽  
Age Group ◽  
Fallopian Tubes ◽  
Potential Accuracy ◽  
Tubal Pathology

The patients investigated under this study have complaints of inability to conception and they were not responding to treatment. Patients with infertility were studied, the peak incidence of infertility was found in between 26-29 years of age group. Hysterosalpingography examination detected tubal and uterine pathology correctly in 26 cases (81.25%) out of 29 cases of complaining of infertility. Of 18 negative cases, 12 cases (80%) are diagnosed correctly as normal by Hysterosalpingography. After laparoscopic examination it was established that three (20%) were false positive and 6 cases were false negative. If a longer series are analyzed, these findings may vary slightly but still it is very useful diagnostic tool for detection of infertility. Hysterosalpingography will give utmost benefit to the patients of our country. In our study we found that Hysterosalpingography is still the best technique for intrauterine and tubal pathology. This study has established the fact that Hysterosalpingography should be the first approach in the diagnosis of infertility which gives valuable information about both uterine cavity and fallopian tubes at low risk and minimal hazards. As a result of our findings, it is our investigation of female infertility due to its potential accuracy and easy performance Keywords: Hysterosalpingography; Infertility. DOI: 10.3329/bmj.v39i1.6228 Bangladesh Medical Journal 2010; 39(1): 16-23

scholarly journals The Identification of Levels of Concept Understanding Using Three-Tier Multiple Choice Diagnostic Test

2019 ◽  
Vol 4 (2) ◽  
pp. 1
Author(s):  
Witri Adriani ◽  
Syamsurizal Syamsurizal ◽  
Ganda Hijrah Selaras ◽  
Relsas Yogica
Keyword(s):  
Diagnostic Test ◽  
False Positive ◽  
False Negative ◽  
Multiple Choice ◽  
Virus Infections ◽  
Virus Classification ◽  
Concept Understanding ◽  
Descriptive Research ◽  
Test Instrument

This research aims at identifiying the levels of concept understanding on virus material at class X, SMA Pertiwi 1 Padang. This is a descriptive research involved 138 students from class X, SMA Pertiwi 1 Padang. This research used Three-Tier Multiple Choice diagnostic test instrument which categorized into three question levels. The results showed that students experienced the highest level of concept understanding on prevented virus infections with 53,87%, then followed with the highest level of  full misconception on the role of the beneficial virus with 36,23%, the highest level of misconception false positive on the different virus and bactery with 12,32%, the highest level of misconception false negative on virus living with 14,49%, the highest level of guessing on virus’ classification with  7,61%, and the highest level of ununderstandable of virus replication’s cycles with 52,18%. Most of students experienced low criteria of the concept material of virus with 34,38%.

scholarly journals Factors Affecting Knowledge Management and Its Effect on Organizational Performance: Mediating the Role of Human Capital

2021 ◽  
Vol 2021 ◽  
pp. 1-16
Author(s):  
Forouzan Rezaei ◽  
Mohammad Khalilzadeh ◽  
Paria Soleimani
Keyword(s):  
Human Capital ◽  
Knowledge Management ◽  
Organizational Performance ◽  
Management Practices ◽  
Steel Plant ◽  
Test Statistic ◽  
Factors Affecting ◽  
Positive Effects ◽  
The Impact

This study aims to investigate and identify the factors affecting the empowerment and implementation of knowledge management in organizations as well as the impact of knowledge management on organizational performance. This study also examines the mediating role of human capital in the relationship between knowledge management and performance of Kabul Steel Plant, which is the largest steel plant in Afghanistan. The research model was developed through the literature review. The initial data were collected through a questionnaire containing 48 questions. Participants were 108 managers and administrative staff of the company. The collected data were analyzed by using the SPSS and SmartPLS software. The hypotheses regarding the impact of strategy and technology on knowledge management were rejected by using correlation analysis and t-test statistic. Finally, the findings showed the positive effects of variables of structure, culture, leadership, and trust on knowledge management in an organization. Also, knowledge management influences the organizational performance, both directly and through the mediating variable of human capital. This research encourages the managers and employees of organizations to use the available organizational resources to implement knowledge management in organizations and improve knowledge management practices and human resources that are the most valuable resources of any organization in order to remain competitive in the markets.

scholarly journals Power Analysis of C-TDT for Small Sample Size Genome-Wide Association Studies by the Joint Use of Case-Parent Trios and Pairs

2013 ◽  
Vol 2013 ◽  
pp. 1-7 ◽  
Author(s):  
Farid Rajabli ◽  
Gul Inan ◽  
Ozlem Ilk
Keyword(s):  
False Positive ◽  
Association Studies ◽  
False Positive Rate ◽  
Small Sample ◽  
Genome Wide Association ◽  
Sample Sizes ◽  
Test Statistic ◽  
Genome Wide ◽  
Positive Rate ◽  
Family Based

In family-based genetic association studies, it is possible to encounter missing genotype information for one of the parents. This leads to a study consisting of both case-parent trios and case-parent pairs. One of the approaches to this problem is permutation-based combined transmission disequilibrium test statistic. However, it is still unknown how powerful this test statistic is with small sample sizes. In this paper, a simulation study is carried out to estimate the power and false positive rate of this test across different sample sizes for a family-based genome-wide association study. It is observed that a statistical power of over 80% and a reasonable false positive rate estimate can be achieved even with a combination of 50 trios and 30 pairs when 2% of the SNPs are assumed to be associated. Moreover, even smaller samples provide high power when smaller percentages of SNPs are associated with the disease.

Critical Evaluation of Impedance Phlebography for the Diagnosis of Deep Vein Thrombosis

1974 ◽  
Vol 31 (02) ◽  
pp. 273-278
Author(s):  
Kenneth K Wu ◽  
John C Hoak ◽  
Robert W Barnes ◽  
Stuart L Frankel
Keyword(s):  
Deep Vein Thrombosis ◽  
False Positive ◽  
False Negative ◽  
Critical Evaluation ◽  
Original Method ◽  
Vein Thrombosis ◽  
Negative Results ◽  
False Negative Results ◽  
Deep Vein ◽  
Positive Results

SummaryIn order to evaluate its daily variability and reliability, impedance phlebography was performed daily or on alternate days on 61 patients with deep vein thrombosis, of whom 47 also had 125I-fibrinogen uptake tests and 22 had radiographic venography. The results showed that impedance phlebography was highly variable and poorly reliable. False positive results were noted in 8 limbs (18%) and false negative results in 3 limbs (7%). Despite its being simple, rapid and noninvasive, its clinical usefulness is doubtful when performed according to the original method.

On the Methodology of Cartel agreements analysis

2014 ◽  
pp. 53-64 ◽  
Author(s):  
E. Andreyashchenko ◽  
A. Zazdravnykh
Keyword(s):  
Economic Models ◽  
Social Consequences ◽  
Positive Effects ◽  
Industrial Markets

This article is an attempt of summarizing key economic approaches to cartel agreements analysis, its stability, ways of estimating social consequences of cartel agreements. It is alleged that the traditional way of understanding the cartels’ role as completely negative is not accurate; this type of inter-corporate agreements may also bring positive effects on industrial markets. Typical limits of analytical apparatus, contradictions that appear while interpreting results of specific economic models are also represented in the article, as well as substantiation of a discrete role of pricing factor within the analysis of anti-competitive agreements.

Peranan Negara dalam Liberalisasi Ekonomi Vietnam: Analisis Terhadap Dasar Doi Moi 1986

2020 ◽  
Author(s):  
Muhamad Helmy Sabtu ◽  
◽  
Khairul Azman Mohamad Suhaimy ◽  
Nurul Aimi Razali
Keyword(s):  
Gender Equality ◽  
Foreign Investment ◽  
Economic Performance ◽  
Level Of Education ◽  
Positive Effects ◽  
Doi Moi ◽  
The People ◽  
Effective Policy ◽  
Economic Landscape

This article analyses the role of state in the policy of economic liberalisation in Vietnam. Doi Moi, which was launched in 1986, is a very influential and effective policy in changing the socio-economic landscape of the people in the country. The results of this study prove that there are positive effects on the increase of foreign investment inflows, the eradication of starvation and unruly poverty, the increase of level of education, the improvement of gender equality and women's rights as well as the sustainability of the environment after Doi Moi is implemented. Through Doi Moi, Vietnam is moving towards a developing country status with good economic performance both at the Southeast Asian and global.

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