scholarly journals True positive fraction

2018 ◽  
Author(s):  
Margaret Pepe
Keyword(s):  
True Positive ◽  
Positive Fraction

scholarly journals Statistical Methods for Evaluating DNA Methylation as a Marker for Early Detection or Prognosis

2007 ◽  
Vol 23 (1-2) ◽  
pp. 113-120 ◽  
Author(s):  
Todd A. Alonzo ◽  
Kimberly D. Siegmund
Keyword(s):  
Dna Methylation ◽  
Statistical Methods ◽  
False Positive ◽  
Classification Accuracy ◽  
Error Rates ◽  
True Positive ◽  
Time To Death ◽  
Methylation Marker ◽  
Positive Fraction ◽  
Time Invariant

We summarize standard and novel statistical methods for evaluating the classification accuracy of DNA methylation markers. The choice of method will depend on the type of marker studied (qualitative/quantitative), the number of markers, and the type of outcome (time-invariant/time-varying). A minimum of two error rates are needed for assessing marker accuracy: the true-positive fraction and the false-positive fraction. Measures of association that are computed from the combination of these error rates, such as the odds ratio or relative risk, are not informative about classification accuracy. We provide an example of a DNA methylation marker that is strongly associated with time to death (logrankp= 0.0003) that is not a good classifier as evaluated by the true-positive and false-positive fractions. Finally, we would like to emphasize the importance of study design. Markers can behave differently in different groups of individuals. It is important to know what factors may affect the accuracy of a marker and in which subpopulations the marker may be more accurate. Such an understanding is extremely important when comparing marker accuracy in two groups of subjects.

scholarly journals Using Relative Statistics and Approximate Disease Prevalence to Compare Screening Tests

2016 ◽  
Vol 12 (2) ◽  
Author(s):  
Frank Samuelson ◽  
Craig Abbey
Keyword(s):  
False Negative ◽  
Roc Curves ◽  
Disease Prevalence ◽  
Screening Tests ◽  
True Positive ◽  
Detection Rates ◽  
Reference Procedure ◽  
Positive Fraction ◽  
Relative Specificity ◽  
Conditional Statistics

Abstract:Schatzkin et al. and other authors demonstrated that the ratios of some conditional statistics such as the true positive fraction are equal to the ratios of unconditional statistics, such as disease detection rates, and therefore we can calculate these ratios between two screening tests on the same population even if negative test patients are not followed with a reference procedure and the true and false negative rates are unknown. We demonstrate that this same property applies to an expected utility metric. We also demonstrate that while simple estimates of relative specificities and relative areas under ROC curves (AUC) do depend on the unknown negative rates, we can write these ratios in terms of disease prevalence, and the dependence of these ratios on a posited prevalence is often weak particularly if that prevalence is small or the performance of the two screening tests is similar. Therefore we can estimate relative specificity or AUC with little loss of accuracy, if we use an approximate value of disease prevalence.

scholarly journals PRATD: A Phased Remote Access Trojan Detection Method with Double-Sided Features

Electronics ◽  
2020 ◽  
Vol 9 (11) ◽  
pp. 1894
Author(s):  
Chun Guo ◽  
Zihua Song ◽  
Yuan Ping ◽  
Guowei Shen ◽  
Yuhei Cui ◽  
...  
Keyword(s):  
False Positive ◽  
Detection Method ◽  
False Positive Rate ◽  
True Positive Rate ◽  
Remote Access ◽  
Detection Methods ◽  
Security Threats ◽  
True Positive ◽  
Trojan Detection ◽  
Positive Rate

Remote Access Trojan (RAT) is one of the most terrible security threats that organizations face today. At present, two major RAT detection methods are host-based and network-based detection methods. To complement one another’s strengths, this article proposes a phased RATs detection method by combining double-side features (PRATD). In PRATD, both host-side and network-side features are combined to build detection models, which is conducive to distinguishing the RATs from benign programs because that the RATs not only generate traffic on the network but also leave traces on the host at run time. Besides, PRATD trains two different detection models for the two runtime states of RATs for improving the True Positive Rate (TPR). The experiments on the network and host records collected from five kinds of benign programs and 20 famous RATs show that PRATD can effectively detect RATs, it can achieve a TPR as high as 93.609% with a False Positive Rate (FPR) as low as 0.407% for the known RATs, a TPR 81.928% and FPR 0.185% for the unknown RATs, which suggests it is a competitive candidate for RAT detection.

scholarly journals PR interval as a predictor of syncope in tilt-up testing in adolescents and young adults

2021 ◽  
Vol 73 (1) ◽  
Author(s):  
Juraj Jug ◽  
Lada Bradić ◽  
Rea Levicki ◽  
Martina Lovrić Benčić
Keyword(s):  
Heart Rate ◽  
Vasovagal Syncope ◽  
True Positive ◽  
Ecg Monitoring ◽  
Interval Prolongation ◽  
Patient History ◽  
Pr Interval ◽  
Heart Rate Dynamics ◽  
Testing Data ◽  
Consciousness Disorder

Abstract Background Syncope, as the most frequent consciousness disorder, is very common in young individuals. The aim of this study was to analyze ECG parameters and clinical properties obtained during tilt-up testing in 12 to 30-year-old subjects. We enrolled a total of 142 patients from our outpatient clinic (39 males, 103 females) with a true positive tilt-up test and analyzed ECG records obtained during tilt-testing. Data were stratified according to the age, gender, and type of syncope. Results PR interval shortening preceding syncope was found in all syncope types, irrespective of the gender. All types of syncope were more frequent in women (72.5%). Mixed syncope type was found to be the most common (47.18%). Male and female subjects differed in initial heart rate (71.56 vs 76.23/min, p=0.05), as well as heart rate dynamics during tilt-up testing. A gender difference was also found in systolic blood pressure (116.92 vs 110.44 mmHg, p<0.01), time to syncope onset (20.77 vs. 16.44 min, p=0.03), and the total number of syncopal episodes in patient history (2.79 vs. 4.62, p<0.05). Subjects with cardioinhibitory syncope had the longest PR interval (average 154.3 ms). PR interval prolongation and loss of variability during tilt-up testing positively correlated with aging (r=0.22, p<0.05). Nodal rhythm was found in 8 patients. Conclusion PR interval shortening on ECG tracings during a tilt-up test can be found in all subtypes of vasovagal syncope, thereby contrasting previous reports that these changes are a hallmark of the cardioinhibitory type of syncope. PR shortening, if observed during ECG monitoring, could be a potential predictor of syncope.

scholarly journals Classifying the Biological Status of Honeybee Workers Using Gas Sensors

Sensors ◽  
2020 ◽  
Vol 21 (1) ◽  
pp. 166
Author(s):  
Jakub T. Wilk ◽  
Beata Bąk ◽  
Piotr Artiemjew ◽  
Jerzy Wilde ◽  
Maciej Siuda
Keyword(s):  
Gas Sensors ◽  
Laboratory Tests ◽  
Test Chamber ◽  
Ambient Air ◽  
True Positive Rate ◽  
True Positive ◽  
Positive Rate ◽  
Parameters Of Accuracy ◽  
Selection Of

Honeybee workers have a specific smell depending on the age of workers and the biological status of the colony. Laboratory tests were carried out at the Department of Apiculture at UWM Olsztyn, using gas sensors installed in two twin prototype multi-sensor detectors. The study aimed to compare the responses of sensors to the odor of old worker bees (3–6 weeks old), young ones (0–1 days old), and those from long-term queenless colonies. From the experimental colonies, 10 samples of 100 workers were taken for each group and placed successively in the research chambers for the duration of the study. Old workers came from outer nest combs, young workers from hatching out brood in an incubator, and laying worker bees from long-term queenless colonies from brood combs (with laying worker bee’s eggs, humped brood, and drones). Each probe was measured for 10 min, and then immediately for another 10 min ambient air was given to regenerate sensors. The results were analyzed using 10 different classifiers. Research has shown that the devices can distinguish between the biological status of bees. The effectiveness of distinguishing between classes, determined by the parameters of accuracy balanced and true positive rate, of 0.763 and 0.742 in the case of the best euclidean.1nn classifier, may be satisfactory in the context of practical beekeeping. Depending on the environment accompanying the tested objects (a type of insert in the test chamber), the introduction of other classifiers as well as baseline correction methods may be considered, while the selection of the appropriate classifier for the task may be of great importance for the effectiveness of the classification.

scholarly journals Effect of Point-Spread Function Reconstruction for Indeterminate PSMA-RADS-3A Lesions on PSMA-Targeted PET Imaging of Men with Prostate Cancer

Diagnostics ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 665
Author(s):  
Wajahat Khatri ◽  
Hyun Woo Chung ◽  
Rudolf A. Werner ◽  
Jeffrey P. Leal ◽  
Kenneth J. Pienta ◽  
...  
Keyword(s):  
Prostate Cancer ◽  
Soft Tissue ◽  
Point Spread Function ◽  
Prospective Trial ◽  
Blood Pool ◽  
True Positive ◽  
Point Spread ◽  
Standardized Uptake Values ◽  
Spread Function

Purpose: Prostate-specific membrane antigen (PSMA) positron emission tomography (PET) is emerging as an important modality for imaging patients with prostate cancer (PCa). As with any imaging modality, indeterminate findings will arise. The PSMA reporting and data system (PSMA-RADS) version 1.0 codifies indeterminate soft tissue findings with the PSMA-RADS-3A moniker. We investigated the role of point-spread function (PSF) reconstructions on categorization of PSMA-RADS-3A lesions. Methods: This was a post hoc analysis of an institutional review board approved prospective trial. Around 60 min after the administration of 333 MBq (9 mCi) of PSMA-targeted 18F-DCFPyL, patients underwent PET/computed tomography (CT) acquisitions from the mid-thighs to the skull vertex. The PET data were reconstructed with and without PSF. Scans were categorized according to PSMA-RADS version 1.0, and all PSMA-RADS-3A lesions on non-PSF images were re-evaluated to determine if any could be re-categorized as PSMA-RADS-4. The maximum standardized uptake values (SUVs) of the lesions, mean SUVs of blood pool, and the ratios of those values were determined. Results: A total of 171 PSMA-RADS-3A lesions were identified in 30 patients for whom both PSF reconstructions and cross-sectional imaging follow-up were available. A total of 13/171 (7.6%) were re-categorized as PSMA-RADS-4 lesions with PSF reconstructions. A total of 112/171 (65.5%) were found on follow-up to be true positive for PCa, with all 13 of the re-categorized lesions being true positive on follow-up. The lesions that were re-categorized trended towards having higher SUVmax-lesion and SUVmax-lesion/SUVmean-blood-pool metrics, although these relationships were not statistically significant. Conclusions: The use of PSF reconstructions for 18F-DCFPyL PET can allow the appropriate re-categorization of a small number of indeterminate PSMA-RADS-3A soft tissue lesions as more definitive PSMA-RADS-4 lesions. The routine use of PSF reconstructions for PSMA-targeted PET may be of value at those sites that utilize this technology.

The Heartbeat Classification Based on PCA

2012 ◽  
Vol 195-196 ◽  
pp. 402-406
Author(s):  
Xue Qin Chen ◽  
Rui Ping Wang
Keyword(s):  
Principal Component Analysis ◽  
Pattern Recognition ◽  
Recognition Task ◽  
Principal Component ◽  
True Positive Rate ◽  
True Positive ◽  
Heartbeat Classification ◽  
Positive Rate ◽  
Electrocardiogram Ecg ◽  
Pattern Recognition Task

Classify the electrocardiogram (ECG) into different pathophysiological categories is a complex pattern recognition task which has been tried in lots of methods. This paper will discuss a method of principal component analysis (PCA) in exacting the heartbeat features, and a new method of classification that is to calculate the error between the testing heartbeat and reconstructed heartbeat. Training and testing heartbeat is taken from the MIT-BIH Arrhythmia Database, in which 8 types of arrhythmia signals are selected in this paper. The true positive rate (TPR) is 83%.

scholarly journals The influence of digital PET/CT on diagnostic certainty and interrater reliability in [68Ga]Ga-PSMA-11 PET/CT for recurrent prostate cancer

2021 ◽  
Author(s):  
Ian Alberts ◽  
Jan-Niklas Hünermund ◽  
Christos Sachpekidis ◽  
Clemens Mingels ◽  
Viktor Fech ◽  
...  
Keyword(s):  
Prostate Cancer ◽  
Interrater Reliability ◽  
True Positive Rate ◽  
True Positive ◽  
Recurrent Prostate Cancer ◽  
Pathological Lesions ◽  
Diagnostic Certainty ◽  
Pet Ct ◽  
Positive Rate ◽  
Digital Pet

Abstract Objective To investigate the impact of digital PET/CT on diagnostic certainty, patient-based sensitivity and interrater reliability. Methods Four physicians retrospectively evaluated two matched cohorts of patients undergoing [68Ga]Ga-PSMA-11 PET/CT on a digital (dPET/CT n = 65) or an analogue scanner (aPET/CT n = 65) for recurrent prostate cancer between 11/2018 and 03/2019. The number of equivocal and pathological lesions as well as the frequency of discrepant findings and the interrater reliability for the two scanners were compared. Results dPET/CT detected more lesions than aPET/CT (p < 0.001). A higher number of pathological scans were observed for dPET/CT (83% vs. 57%, p < 0.001). The true-positive rate at follow-up was 100% for dPET/CT compared to 84% for aPET/CT (p < 0.001). The proportion of lesions rated as non-pathological as a total of all PSMA-avid lesions detected for dPET/CT was comparable to aPET/CT (61.8% vs. 57.0%, p = 0.99). Neither a higher rate of diagnostically uncertain lesions (11.5% dPET/CT vs. 13.7% aPET/CT, p = 0.95) nor discrepant scans (where one or more readers differed in opinion as to whether the scan is pathological) were observed (18% dPET/CT vs. 17% aPET/CT, p = 0.76). Interrater reliability for pathological lesions was excellent for both scanner types (Cronbach’s α = 0.923 dPET/CT; α = 0.948 aPET/CT) and interrater agreement was substantial for dPET/CT (Krippendorf’s α = 0.701) and almost perfect in aPET/CT (α = 0.802). Conclusions A higher detection rate for pathological lesions for dPET/CT compared with aPET/CT in multiple readers was observed. This improved sensitivity was coupled with an improved true-positive rate and was not associated with increased diagnostic uncertainty, rate of non-specific lesions, or reduced interrater reliability. Key Points • New generation digital scanners detect more cancer lesions in men with prostate cancer. • When using digital scanners, the doctors are able to diagnose prostate cancer lesions with better certainty • When using digital scanners, the doctors do not disagree with each other more than with other scanner types.

scholarly journals The Value of Cognitive Pretesting: Improving Validity and Revealing Blind Spots through the Development of a Newborn Screening Parent Experiences Survey

2021 ◽  
Vol 7 (3) ◽  
pp. 41
Author(s):  
Norma-Jean Simon ◽  
Anne Atkins ◽  
Brianne Miller ◽  
Natasha Bonhomme ◽  
Beth Tarini
Keyword(s):  
Newborn Screening ◽  
The United States ◽  
True Positive ◽  
Test Results ◽  
Parent Experiences ◽  
Survey Questions ◽  
Study Team ◽  
Ages And Stages Questionnaires ◽  
Cognitive Pretesting ◽  
Blind Spots

Surveys are used to gather a range of data on newborn screening (NBS) processes. We describe the development of a survey about parents’ NBS experiences, in the United States, informed by cognitive pretest interviews among parents with varying NBS test results (true-positive, false-positive, normal). Cognitive pretest interviews were conducted following a semi-structured script and notes were taken to identify problematic survey items. The study team met weekly to discuss pretest feedback, draft changes, and generate revised items. Pretests indicated that parent experiences with NBS are varied and NBS screening procedures are not well understood. Substantial modifications were made to survey questions concerning NBS testing and result communication. Pretesters often associated NBS with other tests/exams/scales—APGAR scores, Ages and Stages questionnaires, and genetic testing during pregnancy. Some pretesters recalled receiving NBS blood spot results during their hospital admission, an uncommon practice, and few recalled knowing results would be provided to them or their pediatrician in the first few weeks of life. Thorough explanations regarding NBS procedures and expectations were embedded within the survey to enhance and improve interpretation of survey questions. Future NBS experience surveys should utilize cognitive pretesting to capture divergent experiences and improve response validity.

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