scholarly journals Sample size and the multivariate kernel density likelihood ratio: How many speakers are enough?

2017 ◽  
Vol 94 ◽  
pp. 15-29 ◽  
Author(s):  
Vincent Hughes
Keyword(s):  
Sample Size ◽  
Likelihood Ratio ◽  
Kernel Density

scholarly journals A20 DIAGNOSTIC ACCURACY OF A LOW COST, WIDELY AVAILABLE TEST STRIP FOR PREDICTING A POSITIVE FECAL CALPROTECTIN TEST

2021 ◽  
Vol 4 (Supplement_1) ◽  
pp. 210-212
Author(s):  
R Trasolini ◽  
S Wong ◽  
B Salh
Keyword(s):  
Sample Size ◽  
Likelihood Ratio ◽  
Gold Standard ◽  
Low Cost ◽  
Positive Likelihood Ratio ◽  
Negative Likelihood Ratio ◽  
Rapid Test ◽  
Test Strip ◽  
Fecal Calprotectin ◽  
Type I

Abstract Background Fecal calprotectin is a non-invasive test of colonic inflammation used for monitoring inflammatory bowel disease activity and for risk stratifying non-specific colonic symptoms. Calprotectin is a leukocyte specific enzyme. A similar test, leukocyte esterase is used to detect leukocytes in urine and is widely available as a low-cost point-of-care test strip. We hypothesize that an unmodified version of the urine test strip would be highly accurate in predicting a positive fecal calprotectin test in a real world sample of patients. Aims To explore a low cost, rapid alternative to the fecal calprotectin test Methods All inpatient and outpatient stool samples tested for calprotectin by the Vancouver General Hospital laboratory from February 2020 to November 2020 were included prospectively. Samples were simultaneously tested for fecal leukocyte esterase using an unmodified Roche Cobas Chemstrip urinalysis test strip by central lab personnel. An identical aliquot was sent to LifeLabs for calprotectin as per standard protocol. All samples were suspended in buffer using established laboratory protocols prior to testing. Fecal leukocyte esterase results were reported as 0–4+ based on visual interpretation, calprotectin results were reported as mcg/g of stool. REB review and approval was obtained prior to data collection. Sensitivity, Specificity and AUROC were calculated using Microsoft Excel and JROCFIT. Results 26 samples were collected. Using a fecal calprotectin greater than 120 mcg/g as a gold standard an AUROC of 0.89 (SE= .06) was calculated. A leukocyte esterase reading of 2+ or greater had the best test characteristics based on ROC curve analysis. Using this cutoff, 21/26 samples were concordant, giving an accuracy of 80.8%, sensitivity of 90.9% and specificity of 73.3%. Positive likelihood ratio was 8.07 and negative likelihood ratio was 0.29. Assuming an AUROC of 0.8, the sample size N=26 is 90% powered (β=0.9) to predict the true AUROC within 0.1 with a type I error rate of .05 (α<.05). Conclusions This study suggests application of a prepared stool sample to a urinalysis test strip gives a result highly predictive of a positive fecal calprotectin test. Further results are being collected prospectively to improve the robustness of these preliminary data. Secondary outcomes including comparison to endoscopy and biopsy results where available are planned if an adequate sample size can be accrued. Future studies justifying independent clinical use of leukocyte esterase would require a common gold standard comparator such as endoscopy. Fecal calprotectin testing is not universally insured and is not available as a rapid test strip. Use of fecal leukocyte esterase may reduce costs and shorten time to results if proven to be independently reliable. Funding Agencies None

Embedding submartingales in wiener processes with drift, with applications to sequential analysis

1969 ◽  
Vol 6 (03) ◽  
pp. 612-632 ◽  
Author(s):  
W. J. Hall
Keyword(s):  
Lower Bound ◽  
Random Walks ◽  
Sample Size ◽  
Wiener Process ◽  
Likelihood Ratio ◽  
Sequential Analysis ◽  
Stopping Times ◽  
Wiener Processes ◽  
Size Function ◽  
Log Likelihood

Summary Skorokhod (1961) demonstrated how the study of martingale sequences (and zero-mean random walks) can be reduced to the study of the Wiener process (without drift) at a sequence of random stopping times. We show how the study of certain submartingale sequences, including certain random walks with drift and log likelihood ratio sequences, can be reduced to the study of the Wiener process with drift at a sequence of stopping times (Theorem 4.1). Applications to absorption problems are given. Specifically, we present new derivations of a number of the basic approximations and inequalities of classical sequential analysis, and some variations on them — including an improvement on Wald's lower bound for the expected sample size function (Corollary 7.5).

scholarly journals Rapid Sample Size Calculations for a Defined Likelihood Ratio Test-Based Power in Mixed-Effects Models

2012 ◽  
Vol 14 (2) ◽  
pp. 176-186 ◽  
Author(s):  
Camille Vong ◽  
Martin Bergstrand ◽  
Joakim Nyberg ◽  
Mats O. Karlsson
Keyword(s):  
Sample Size ◽  
Likelihood Ratio ◽  
Likelihood Ratio Test ◽  
Mixed Effects ◽  
Mixed Effects Models ◽  
Ratio Test ◽  
Sample Size Calculations

scholarly journals Diagnostic Value of CircRNAs as Potential Biomarkers in Oral Squamous Cell Carcinoma: a Meta-Analysis

2021 ◽  
Vol 11 ◽  
Author(s):  
Mingfei Wang ◽  
Linfeng Zhang ◽  
Wenhao Ren ◽  
Shaoming Li ◽  
Keqian Zhi ◽  
...  
Keyword(s):  
Systematic Review ◽  
Squamous Cell Carcinoma ◽  
Oral Squamous Cell Carcinoma ◽  
Sample Size ◽  
Cell Carcinoma ◽  
Likelihood Ratio ◽  
Squamous Cell ◽  
Meta Analysis ◽  
Cochrane Library ◽  
Potential Biomarkers

IntroductionCircular RNAs (CircRNAs), an emerging non-coding RNA, have been demonstrated to be involved in tumorigenesis, metastasis, and cancer progression, and could represent novel potential biomarkers for diagnosing oral squamous cell carcinoma (OSCC). However, no meta-analysis has investigated the diagnostic role of circRNAs in OSCC. Hence, to investigate whether circRNAs could serve as specific biomarkers for OSCC, the present systematic review and meta-analysis evaluated the diagnostic efficiency of circRNAs in patients with OSCC.Materials and MethodsA thorough search of online databases (Pubmed, Web of Science, Embase, and the Cochrane Library) was conducted to collect relevant studies up to March 30th, 2021. All eligible studies were case-control studies. The quality of each study was evaluated by the Quality Assessment of Diagnostic Accuracy Studies-2 (QUADAS-2) tool. STATA (version 15.1) and Review Manager (version 5.4) were employed to conduct the meta-analysis, and the PRISMA statement was adopted in this study.ResultsA total of 16 studies were included in the meta-analysis, with five studies on upregulated circRNAs, and 11 on downregulated circRNAs. The enrolled studies that met our eligibility criteria all derived from China. The pooled sensitivity (SEN), specificity (SPE), diagnostic odds ratio (DOR), positive likelihood ratio (PLR), negative likelihood ratio (NLR), and the area under receiver operating characteristics curve (AUC) with the 95% confidence intervals (95% CIs) were 0.74 (0.69–0.79), 0.79 (0.73–0.84), 10.74 (7.81–14.77), 3.50 (2.78–4.45), 0.33 (0.27–0.39) and 0.83 (0.79–0.86), respectively. The subgroup analysis demonstrated that serum, plasma, and saliva specimens had a better diagnostic performance than tissue samples, with a high value of sensitivity, specificity, DOR, and AUC values. The results also showed that the subgroups of upregulated circRNAs and a sample size of ≥100 manifested higher specificity, DOR, and AUC for cancer detection than downregulated circRNAs and a sample size of < 100.ConclusionsA strong association was demonstrated between the dysregulated expression of circRNAs and the diagnosis of OSCC. Hence, circRNAs have the potential to function as promising biomarkers and therapeutic targets for OSCC.Systematic Review RegistrationPROSPERO, number CRD42021256857.

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