scholarly journals Optimal response biases and the slope of ROC curves as a function of signal intensity, signal probability, and relative payoff

1974 ◽  
Vol 16 (2) ◽  
pp. 377-384 ◽  
Author(s):  
Ann L. Hume
Keyword(s):  
Signal Intensity ◽  
Roc Curves ◽  
Signal Probability ◽  
Optimal Response ◽  
Relative Payoff ◽  
Response Biases

scholarly journals Value of 3D MRI and Vaginal Opacification for the Diagnosis of Vaginal Endometriosis

2020 ◽  
Vol 7 ◽  
Author(s):  
Marc Bazot ◽  
Selma Beldjord ◽  
Lamia Jarboui ◽  
Clement Ferrier ◽  
Sofiane Bendifallah ◽  
...  
Keyword(s):  
Signal Intensity ◽  
Descriptive Analysis ◽  
Three Dimensional ◽  
Roc Curves ◽  
High Signal Intensity ◽  
High Signal ◽  
3D Mri ◽  
Likelihood Ratios ◽  
Additional Value ◽  
Vaginal Endometriosis

Objective: The aim of the study was to evaluate three-dimensional (3D) T2 MRI before and after vaginal opacification (VO) by gel (3DT2VO) and the additional value of 3DT1 with fat-suppression (3DT1FS) MRI in the diagnosis of vaginal endometriosis.Methods: In this study conducted from 2010 to 2013, 51 patients scheduled for surgical treatment of endometriosis underwent MRI 1 day before surgery. Three readers (novice, intermediate, expert) were asked to retrospectively diagnose vaginal endometriosis independently and blindly using four different readings (i.e., 3DT2, 3DT2VO, 3DT2 with 3DT1FS, 3DT2VO with 3DT1FS). Vaginal endometriosis diagnosis was positive on observation of a thickening of vaginal walls on 3DT2 with or without high-signal-intensity spots on 3DT2 and/or 3DT1FS. The reference standard was surgery and histology. Descriptive analysis, Chi-square test, and ROC curves were used for statistical analysis.Results: For all readers, the combination of 3DT2 and 3DT1FS significantly improved the diagnosis of vaginal endometriosis compared with 3DT2 (p = 0.002, p = 0.02, and p = 0.003). 3DT2VO significantly improved diagnosis for the intermediate reader (p = 0.01). High-signal-intensity spots on 3DT1FS had a sensitivity of 50–63.6%, specificity of 86.2–96.6%, and high positive likelihood ratios (14.5-Inf).Conclusion: 3DT2 in association with 3DT1FS appears to be the best 3D MRI protocol for the diagnosis of vaginal endometriosis, whatever the level of experience of readers. The additional value of 3DT2VO is variable among the readers.

Effects of Signal Probability on Vibrotactile Signal Recognition

1974 ◽  
Vol 38 (1) ◽  
pp. 15-23 ◽  
Author(s):  
George A. Gescheider
Keyword(s):  
Performance Optimization ◽  
Signal Intensity ◽  
Operating Characteristic ◽  
Decision Criterion ◽  
Signal Probability ◽  
Signal Recognition ◽  
Strong Response ◽  
Receiver Operating Characteristic Curves ◽  
Strong Signal ◽  
Probability Information

When signal intensity was set at either 20 or 21 dB SL, O was required to report whether the 60-Hz vibration on his fingertip was strong or weak. If trial-by-trial feedback was given, increasing the probability of a strong signal led to an increase in the probability of a “strong” response. The shape of receiver-operating-characteristic curves was consistent with the assumption of the theory of signal detection that performance optimization is accomplished by O making an appropriate change in the location of his decision criterion. When O was not told the signal probability or given trial-by-trial feedback the proportion of strong responses decreased as signal probability was increased. The performance optimization that occurred when feedback was given was facilitated by also telling O the signal probabiliry. When signal-probability information but no feedback is given, performance is likely to be unaffected by changes in signal probability.

High BCR-ABL/GUSIS Levels at Diagnosis Are Associated with Unfavorable Responses to Standard Dose Imatinib

Blood ◽  
2015 ◽  
Vol 126 (23) ◽  
pp. 4049-4049 ◽  
Author(s):  
Paolo Vigneri ◽  
Fabio Stagno ◽  
Stefania Stella ◽  
Alessandra Cupri ◽  
Stefano Forte ◽  
...  
Keyword(s):  
Tyrosine Kinase ◽  
Research Funding ◽  
Kinase Inhibitors ◽  
Kinase Inhibitor ◽  
Standard Dose ◽  
Blast Crisis ◽  
Roc Curves ◽  
Free Survival ◽  
Optimal Response ◽  
Real Time Quantitative Pcr

Abstract Background The approval of second-generation tyrosine kinase inhibitors (TKIs) for the first line treatment of Chronic Myeloid Leukemia (CML) has generated a need for early molecular parameters associated with inadequate responses to Imatinib Mesylate (IM). Objective We correlated quantitative determination of BCR-ABL transcripts at diagnosis with the outcome (defined according to the 2013 European Leukemia Net recommendations) of 272 newly diagnosed CML patients receiving IM 400 mg/die. Methods BCR-ABL transcripts were measured from peripheral blood samples drawn at diagnosis before patients received any pharmacological treatment using Real-Time Quantitative PCR (RQ-PCR). All molecular determinations were performed twice (in triplicates) on the same sample using either ABL or glucuronidase-beta (GUS) as reference genes. BCR-ABL values were then reported on the international scale (IS). Results With a median follow-up of 60 months, 65.4% of patients achieved an optimal response, 5.6% presented a response currently defined as "warning", 22.4% failed IM treatment and 6.6% switched to a different tyrosine kinase inhibitor because of intolerance to the drug. We recorded 19 deaths (6.9%), 7 (2.5%) attributable to disease progression. We applied Receiver Operating Characteristic (ROC) curves to define BCR-ABL/GUSIS expression levels that would separate patients likely (i.e. below the threshold) or unlikely (i.e. above the threshold) to achieve multiple endpoints, namely: optimal response (OR), failure-free survival (FFS), event-free survival (EFS), transformation-free survival (TFS) and overall survival (OS). Employing the specific threshold calculated for each endpoint we found that high BCR-ABL/GUSIS levels at diagnosis were associated with inferior probabilities of OR (p<0.001), FFS (p<0.001) and EFS (p<0.001). Elevated BCR-ABL/GUSIS levels were also associated with higher rates of disease transformation to the accelerated phase or blast crisis (p=0.029) but not with OS (p=0.132). Conclusions High BCR-ABL transcripts at diagnosis measured by RQ-PCR employing GUS as a reference gene allow the identification of CML patients unlikely to benefit from standard dose IM that should be considered for alternative forms of treatment. Disclosures Hochhaus: Novartis: Honoraria, Research Funding; Bristol-Myers Squibb: Honoraria, Research Funding; ARIAD: Honoraria, Research Funding; Pfizer: Honoraria, Research Funding.

scholarly journals Failure to Apply Signal Detection Theory to the Montreal Battery of Evaluation of Amusia May Misdiagnose Amusia

2012 ◽  
Vol 30 (5) ◽  
pp. 480-496 ◽  
Author(s):  
Molly J. Henry ◽  
J. Devin McAuley
Keyword(s):  
Signal Detection ◽  
Response Bias ◽  
Signal Detection Theory ◽  
Roc Curves ◽  
Detection Theory ◽  
Performance Measure ◽  
Evaluation Of Performance ◽  
N 93 ◽  
Response Biases ◽  
Large Response

This article considers a signal detection theory (SDT) approach to evaluation of performance on the Montreal Battery of Evaluation of Amusia (MBEA). One hundred fifty-five individuals completed the original binary response version of the MBEA (n = 62) or a confidence rating version (MBEA-C; n = 93). Confidence ratings afforded construction of empirical receiver operator characteristic (ROC) curves and derivation of bias-free performance measures against which we compared the standard performance metric, proportion correct (PC), and an alternative signal detection metric, d ′. Across the board, PC was tainted by response bias and underestimated performance as indexed by Az, a nonparametric ROC-based performance measure. Signal detection analyses further revealed that some individuals performing worse than the standard PC-based cutoff for amusia diagnosis showed large response biases. Given that PC is contaminated by response bias, this suggests the possibility that categorizing individuals as having amusia or not, using a PC-based cutoff, may inadvertently misclassify some individuals with normal perceptual sensitivity as amusic simply because they have large response biases. In line with this possibility, a comparison of amusia classification using d ′- and PC-based cutoffs showed potential misclassification of 33% of the examined cases.

Magnitude Estimation and Cross-Modal Matching of Lingual Vibrotactile and Auditory Sensation

1989 ◽  
Vol 32 (3) ◽  
pp. 698-702 ◽  
Author(s):  
Daniel Harris ◽  
Donald Fucci ◽  
Linda Petrosino
Keyword(s):  
Auditory Stimulus ◽  
Magnitude Estimation ◽  
Sensory Processing ◽  
Test Site ◽  
Systematic Investigation ◽  
Thenar Eminence ◽  
Stimulus Range ◽  
Psychophysical Scaling ◽  
Scaling Methods ◽  
Response Biases

The present experiment was a preliminary attempt to use the psychophysical scaling methods of magnitude estimation and cross-modal matching to investigate suprathreshold judgments of lingual vibrotactile and auditory sensation magnitudes for 20 normal young adult subjects. A 250-Hz lingual vibrotactile stimulus and a 1000-Hz binaural auditory stimulus were employed. To obtain judgments for nonoral vibrotactile sensory magnitudes, the thenar eminence of the hand was also employed as a test site for 5 additional subjects. Eight stimulus intensities were presented during all experimental tasks. The results showed that the slopes of the log-log vibrotactile magnitude estimation functions decreased at higher stimulus intensity levels for both test sites. Auditory magnitude estimation functions were relatively constant throughout the stimulus range. Cross-modal matching functions for the two stimuli generally agreed with functions predicted from the magnitude estimation data, except when subjects adjusted vibration on the tongue to match auditory stimulus intensities. The results suggested that the methods of magnitude estimation and cross-modal matching may be useful for studying sensory processing in the speech production system. However, systematic investigation of response biases associated with vibrotactile-auditory psychophysical scaling tasks appears to be a prerequisite.

Influence of preoperative statins and aspirin administration on biological and magnetic resonance imaging properties in patients with abdominal aortic aneurysm

VASA ◽  
2020 ◽  
pp. 1-9
Author(s):  
Milos Sladojevic ◽  
Petar Zlatanovic ◽  
Zeljka Stanojevic ◽  
Igor Koncar ◽  
Sasenka Vidicevic ◽  
...  
Keyword(s):  
Magnetic Resonance Imaging ◽  
Abdominal Aortic Aneurysm ◽  
Magnetic Resonance ◽  
Aortic Aneurysm ◽  
Signal Intensity ◽  
Psoas Muscle ◽  
Resonance Imaging ◽  
Maximal Diameter ◽  
Aneurysm Wall ◽  
Abdominal Aortic

Summary: Background: Main objective of this study was to evaluate the influence of statins and/or acetylsalicylic acid on biochemical characteristics of abdominal aortic aneurysm (AAA) wall and intraluminal thrombus (ILT). Patients and methods: Fifty patients with asymptomatic infrarenal AAA were analyzed using magnetic resonance imaging on T1w sequence. Relative ILT signal intensity (SI) was determined as a ratio between ILT and psoas muscle SI. Samples containing the full ILT thickness and aneurysm wall were harvested from the anterior surface at the level of the maximal diameter. The concentration of enzymes such as matrix metalloproteinase (MMP) 9, MMP2 and neutrophil elastase (NE/ELA) were analyzed in ILT and AAA wall; while collagen type III, elastin and proteoglycan 4 were analyzed in harvested AAA wall. Oxidative stress in the AAA wall was assessed by catalase and malondialdehyde activity in tissue samples. Results: Relative ILT signal intensity (1.09 ± 0.41 vs 0.89 ± 0.21, p = 0.013) were higher in non-statin than in statin group. Patients who were taking aspirin had lower relative ILT area (0.89 ± 0.19 vs 1.13. ± 0.44, p = 0.016), and lower relative ILT signal intensity (0.85 [0.73–1.07] vs 1.01 [0.84–1.19], p = 0.021) compared to non-aspirin group. There were higher concentrations of elastin in AAA wall among patients taking both of aspirin and statins (1.21 [0.77–3.02] vs 0.78 (0.49–1.05) ng/ml, p = 0.044) than in patients who did not take both of these drugs. Conclusions: Relative ILT SI was lower in patients taking statin and aspirin. Combination of antiplatelet therapy and statins was associated with higher elastin concentrations in AAA wall.

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