Simple confidence interval and region formulas for comparing diagnostic likelihood ratios under a paired design

2021 ◽  
Author(s):  
Yougui Wu
Keyword(s):  
Confidence Interval ◽  
Likelihood Ratios ◽  
Paired Design

Evaluation of a Prognostic Homeopathic Questionnaire for Women with Premenstrual Disorders

2018 ◽  
Vol 25 (3) ◽  
pp. 173-182
Author(s):  
Christien T. Klein-Laansma ◽  
Alexander L.B. Rutten ◽  
Jean Pierre C.H. Jansen ◽  
Herman van Wietmarschen ◽  
Miek C. Jong
Keyword(s):  
Clinical Practice ◽  
Confidence Interval ◽  
Premenstrual Syndrome ◽  
Prognostic Value ◽  
Premenstrual Dysphoric Disorder ◽  
Patient Questionnaire ◽  
Likelihood Ratios ◽  
Time Points ◽  
Homeopathic Medicine ◽  
Symptom Scores

Background/Aims: Validation of treatments with individually prescribed homeopathic medicines is a challenging task. A prognostic homeopathic patient questionnaire containing 140 keynote symptoms (highly characteristic of a specific homeopathic medicine) and an electronic algorithm to process the answers were used in 2 clinical studies. The algorithm outcome, based on total symptom scores, indicated 1 of 11 pre-selected homeopathic medicines for women with premenstrual syndrome and premenstrual dysphoric disorder (PMS/PMDD). Aims were (1) to estimate the prognostic values of keynote symptoms and (2) to evaluate the reliability of the homeopathic medicine ranking in the algorithm outcome. Methods: The prevalence of specific keynote symptoms was calculated in 145 women diagnosed with PMS/PMDD and in 40 included women with favorable outcomes using 1 of the 11 homeopathic medicines. Likelihood ratios (LRs) of the keynote symptoms were calculated. Pearson's correlations were calculated between 2 sets of total algorithm scores for 11 homeopathic medicines, obtained at 2 time points. Results: (1) A positive prognostic value (LR ≥ 1.5) was found in 34 keynote symptoms with a prevalence of 10-40%, with 10 symptoms already being connected to the corresponding homeopathic medicine in the algorithm. For example, the symptom ‘common cold of the nose before menstruation' indicated Magnesium carbonicum with LR = 7.47 (confidence interval (CI) 3.90-14.28). (2) Pearson's correlations for the reliability evaluation varied from 0.69 to 0.84. Conclusions: Recommendations can be made to improve the PMS algorithm with more accurate keynote symptoms. The prognostic questionnaire proved a reliable tool to rank 11 homeopathic medicines by total scores, based on keynote symptoms. This PMS algorithm can be used for the treatment of PMS/PMDD in clinical practice.

scholarly journals Compbdt: an R program to compare two binary diagnostic tests subject to a paired design

2020 ◽  
Author(s):  
Jose Antonio Roldán-Nofuentes
Keyword(s):  
Confidence Intervals ◽  
Diagnostic Tests ◽  
Null Hypothesis ◽  
Type Ii ◽  
Type Ii Error ◽  
Hypothesis Tests ◽  
Likelihood Ratios ◽  
Predictive Values ◽  
R Program ◽  
Paired Design

Abstract Background: The comparison of the effectiveness of two binary diagnostic tests is an important topic in Clinical Medicine. The most frequent type of sample design to compare two binary diagnostic tests is the paired design. This design consists of applying the two binary diagnostic tests to all of the individuals in a random sample, where the disease status of each individual is known through the application of a gold standard . This article presents an R program to compare parameters of two binary tests subject to a paired design. Results: The “compbdt” program estimates the sensitivity and the specificity, the likelihood ratios and the predictive values of each diagnostic test applying the confidence intervals with the best asymptotic performance. The program compares the sensitivities and specificities of the two diagnostic tests simultaneously, as well as the likelihood ratios and the predictive values, applying the global hypothesis tests with the best performance in terms of Type I error and power. When the global hypothesis test is significant, the causes of the significance are investigated solving the individual hypothesis tests and applying the multiple comparison method of Holm. The most optimal confidence intervals are also calculated for the difference or ratio between the respective parameters. Based on the data observed in the sample, the program also estimates the probability of making a Type II error if the null hypothesis is not rejected, or estimates the power if the if the alternative hypothesis is accepted. The “compbdt” program provides all the necessary results so that the researcher can easily interpret them. The estimation of the probability of making a Type II error allows the researcher to decide about the reliability of the null hypothesis when this hypothesis is not rejected. The “compbdt” program has been applied to a real example on the diagnosis of coronary artery disease. Conclusions: The “compbdt” program is one which is easy to use and allows the researcher to compare the most important parameters of two binary tests subject to a paired design. The “compbdt” program is available as supplementary material.

scholarly journals An epistemic interpretation of the posterior likelihood ratio distribution

2020 ◽  
Vol 19 (2) ◽  
pp. 139-155
Author(s):  
Ronald Meester ◽  
Klaas Slooten
Keyword(s):  
Decision Making ◽  
Confidence Interval ◽  
Likelihood Ratio ◽  
Current Knowledge ◽  
Current Data ◽  
Model Parameters ◽  
Likelihood Ratios ◽  
Ratio Distribution ◽  
Evidential Value ◽  
Epistemic Interpretation

Abstract Often the expression of a likelihood ratio involves model parameters θ. This fact prompted many researchers to argue that a likelihood ratio should be accompanied by a confidence interval, as one would do when estimating θ itself. We first argue against this, based on our view of the likelihood ratio as a function of our knowledge of the model parameters, rather than being a function of the parameters themselves. There is, however, another interval that can be constructed, and which has been introduced in the literature. This is the interval obtained upon sampling from the so-called ‘posterior likelihood ratio distribution’, after removing, say, the most extreme 5% of a sample from this distribution. Although this construction appears in the literature, its interpretation remained unclear, as explicitly acknowledged in the literature. In this article we provide an interpretation: the posterior likelihood ratio distribution tells us which likelihood ratios we can expect if we were to obtain more information. As such, it can play a role in decision making procedures, for instance about the question whether or not it is worthwhile to try to obtain more data. The posterior likelihood ratio distribution has no relevance for the evidential value of the current data with our current knowledge. We illustrate all this with a number of examples.

scholarly journals A Diagnostic Marker to Discriminate Childhood Apraxia of Speech From Speech Delay: II. Validity Studies of the Pause Marker

2017 ◽  
Vol 60 (4) ◽  
Author(s):  
Lawrence D. Shriberg ◽  
Edythe A. Strand ◽  
Marios Fourakis ◽  
Kathy J. Jakielski ◽  
Sheryl D. Hall ◽  
...  
Keyword(s):  
Confidence Interval ◽  
Mayo Clinic ◽  
Diagnostic Marker ◽  
Adult Onset ◽  
Apraxia Of Speech ◽  
Speech Delay ◽  
Likelihood Ratios ◽  
Childhood Apraxia Of Speech ◽  
Acoustic Measures ◽  
Validity Studies

Purpose The purpose of this 2nd article in this supplement is to report validity support findings for the Pause Marker (PM), a proposed single-sign diagnostic marker of childhood apraxia of speech (CAS). Method PM scores and additional perceptual and acoustic measures were obtained from 296 participants in cohorts with idiopathic and neurogenetic CAS, adult-onset apraxia of speech and primary progressive apraxia of speech, and idiopathic speech delay. Results Adjusted for questionable specificity disagreements with a pediatric Mayo Clinic diagnostic standard, the estimated sensitivity and specificity, respectively, of the PM were 86.8% and 100% for the CAS cohort, yielding positive and negative likelihood ratios of 56.45 (95% confidence interval [CI]: [1.15, 2763.31]) and 0.13 (95% CI [0.06, 0.30]). Specificity of the PM for 4 cohorts totaling 205 participants with speech delay was 98.5%. Conclusion These findings are interpreted as providing support for the PM as a near-conclusive diagnostic marker of CAS.

scholarly journals Compbdt: an R program to compare two binary diagnostic tests subject to a paired design

2020 ◽  
Author(s):  
Jose Antonio Roldán-Nofuentes
Keyword(s):  
Confidence Intervals ◽  
Diagnostic Tests ◽  
Null Hypothesis ◽  
Type Ii ◽  
Type Ii Error ◽  
Hypothesis Tests ◽  
Likelihood Ratios ◽  
Predictive Values ◽  
R Program ◽  
Paired Design

Abstract Background: The comparison of the effectiveness of two binary diagnostic tests is an important topic in Clinical Medicine. The most frequent type of sample design to compare two binary diagnostic tests is the paired design. This design consists of applying the two binary diagnostic tests to all of the individuals in a random sample, where the disease status of each individual is known through the application of a gold standard . This article presents an R program to compare parameters of two binary tests subject to a paired design. Results: The “compbdt” program estimates the sensitivity and the specificity, the likelihood ratios and the predictive values of each diagnostic test applying the confidence intervals with the best asymptotic performance. The program compares the sensitivities and specificities of the two diagnostic tests simultaneously, as well as the likelihood ratios and the predictive values, applying the global hypothesis tests with the best performance in terms of Type I error and power. When the global hypothesis test is significant, the causes of the significance are investigated solving the individual hypothesis tests and applying the multiple comparison method of Holm. The most optimal confidence intervals are also calculated for the difference or ratio between the respective parameters. Based on the data observed in the sample, the program also estimates the probability of making a Type II error if the null hypothesis is not rejected, or estimates the power if the if the alternative hypothesis is accepted. The “compbdt” program provides all the necessary results so that the researcher can easily interpret them. The estimation of the probability of making a Type II error allows the researcher to decide about the reliability of the null hypothesis when this hypothesis is not rejected. The “compbdt” program has been applied to a real example on the diagnosis of coronary artery disease. Conclusions: The “compbdt” program is one which is easy to use and allows the researcher to compare the most important parameters of two binary tests subject to a paired design. The “compbdt” program is available as supplementary material.

Development of apical pits in chloride cells of the gills of Pimephales promelas after chronic exposure to acid water

1983 ◽  
Vol 41 ◽  
pp. 462-463
Author(s):  
Richard L. Leino ◽  
Jon G. Anderson ◽  
J. Howard McCormick
Keyword(s):  
Confidence Interval ◽  
Chronic Exposure ◽  
Lake Superior ◽  
Pimephales Promelas ◽  
Chloride Cells ◽  
Fathead Minnows ◽  
Secondary Lamellae ◽  
Untreated Water ◽  
Water Ph ◽  
Flow Through

Groups of 12 fathead minnows were exposed for 129 days to Lake Superior water acidified (pH 5.0, 5.5, 6.0 or 6.5) with reagent grade H2SO4 by means of a multichannel toxicant system for flow-through bioassays. Untreated water (pH 7.5) had the following properties: hardness 45.3 ± 0.3 (95% confidence interval) mg/1 as CaCO3; alkalinity 42.6 ± 0.2 mg/1; Cl- 0.03 meq/1; Na+ 0.05 meq/1; K+ 0.01 meq/1; Ca2+ 0.68 meq/1; Mg2+ 0.26 meq/1; dissolved O2 5.8 ± 0.3 mg/1; free CO2 3.2 ± 0.4 mg/1; T= 24.3 ± 0.1°C. The 1st, 2nd and 3rd gills were subsequently processed for LM (methacrylate), TEM and SEM respectively.Three changes involving chloride cells were correlated with increasing acidity: 1) the appearance of apical pits (figs. 2,5 as compared to figs. 1, 3,4) in chloride cells (about 22% of the chloride cells had pits at pH 5.0); 2) increases in their numbers and 3) increases in the % of these cells in the epithelium of the secondary lamellae.

Sentence Repetition: A Clinical Marker for Developmental Language Disorder in Danish

2019 ◽  
Vol 62 (12) ◽  
pp. 4450-4463
Author(s):  
Rikke Vang Christensen
Keyword(s):  
Language Disorder ◽  
Future Research ◽  
Typically Developing ◽  
Developmental Language Disorder ◽  
Older Children ◽  
Likelihood Ratios ◽  
Clinical Marker ◽  
Sentence Repetition ◽  
Good Identification ◽  
Syntactic Properties

Purpose The aim of the study was to explore the potential of performance on a Danish sentence repetition (SR) task—including specific morphological and syntactic properties—to identify difficulties in children with developmental language disorder (DLD) relative to typically developing (TD) children. Furthermore, the potential of the task as a clinical marker for Danish DLD was explored. Method SR performance of children with DLD aged 5;10–14;1 (years;months; n = 27) and TD children aged 5;3–13;4 ( n = 87) was investigated. Results Compared to TD same-age peers, children with DLD were less likely to repeat the sentences accurately but more likely to make ungrammatical errors with respect to verb inflection and use of determiners and personal pronouns. Younger children with DLD also produced more word order errors that their TD peers. Furthermore, older children with DLD performed less accurately than younger TD peers, indicating that the SR task taps into morphosyntactic areas of particular difficulty for Danish children with DLD. The classification accuracy associated with SR performance showed high levels of sensitivity and specificity (> 90%) and likelihood ratios indicating good identification potential for clinical and future research purposes. Conclusion SR performance has a strong potential for identifying children with DLD, also in Danish, and with a carefully designed SR task, performance has potential for revealing morphosyntactic difficulties. Supplemental Material https://doi.org/10.23641/asha.10314437

Clausal Density Between Ages 4 and 9 Years for the Edmonton Narrative Norms Instrument: Reference Data and Psychometric Properties

2020 ◽  
pp. 1-15
Author(s):  
Ling-Yu Guo ◽  
Phyllis Schneider ◽  
William Harrison
Keyword(s):  
Diagnostic Accuracy ◽  
Psychometric Properties ◽  
Language Impairment ◽  
Reference Data ◽  
Reliability And Validity ◽  
Correlation Coefficients ◽  
Criterion Validity ◽  
Likelihood Ratios ◽  
Generation Task ◽  
Sensitivity Specificity

Purpose This study provided reference data and examined psychometric properties for clausal density (CD; i.e., number of clauses per utterance) in children between ages 4 and 9 years from the database of the Edmonton Narrative Norms Instrument (ENNI). Method Participants in the ENNI database included 300 children with typical language (TL) and 77 children with language impairment (LI) between the ages of 4;0 (years;months) and 9;11. Narrative samples were collected using a story generation task, in which children were asked to tell stories based on six picture sequences. CD was computed from the narrative samples. The split-half reliability, concurrent criterion validity, and diagnostic accuracy were evaluated for CD by age. Results CD scores increased significantly between ages 4 and 9 years in children with TL and those with LI. Children with TL produced higher CD scores than those with LI at each age level. In addition, the correlation coefficients for the split-half reliability and concurrent criterion validity of CD scores were all significant at each age level, with the magnitude ranging from small to large. The diagnostic accuracy of CD scores, as revealed by sensitivity, specificity, and likelihood ratios, was poor. Conclusions The finding on diagnostic accuracy did not support the use of CD for identifying children with LI between ages 4 and 9 years. However, given the attested reliability and validity for CD, reference data of CD from the ENNI database can be used for evaluating children's difficulties with complex syntax and monitoring their change over time. Supplemental Material https://doi.org/10.23641/asha.13172129

Efficacy of Vitamin D on Chronic Heart Failure Among Adults

2020 ◽  
Vol 90 (1-2) ◽  
pp. 49-58 ◽  
Author(s):  
Wang Chunbin ◽  
Wang Han ◽  
Cai Lin
Keyword(s):  
Heart Failure ◽  
Vitamin D ◽  
Chronic Heart Failure ◽  
Left Ventricular Ejection Fraction ◽  
Confidence Interval ◽  
Left Ventricular ◽  
Left Ventricular Ejection ◽  
Controlled Trials ◽  
Ventricular Ejection Fraction ◽  
Randomized Controlled

Abstract. Vitamin D deficiency commonly occurs in chronic heart failure. Whether additional vitamin D supplementation can be beneficial to adults with chronic heart failure remains unclear. We conducted a meta-analysis to derive a more precise estimation. PubMed, Embase, and Cochrane databases were searched on September 8, 2016. Seven randomized controlled trials that investigated the effects of vitamin D on cardiovascular outcomes in adults with chronic heart failure, and comprised 592 patients, were included in the analysis. Compared to placebo, vitamin D, at doses ranging from 2,000 IU/day to 50,000 IU/week, could not improve left ventricular ejection fraction (Weighted mean difference, WMD = 3.31, 95% confidence interval, CL = −0.93 to 7.55, P < 0.001, I2 = 92.1%); it also exerts no beneficial effects on the 6 minute walk distance (WMD = 18.84, 95% CL = −24.85 to 62.52, P = 0.276, I2 = 22.4%) and natriuretic peptide (Standardized mean difference, SMD = −0.39, 95% confidence interval CL = −0.48 to 0.69, P < 0.001, I2 = 92.4%). However, a dose-response analysis from two studies demonstrated an improved left ventricular ejection fraction with vitamin D at a dose of 4,000 IU/day (WMD = 6.58, 95% confidence interval CL = −4.04 to 9.13, P = 0.134, I2 = 55.4%). The results showed that high dose vitamin D treatment could potentially benefit adults with chronic heart failure, but more randomized controlled trials are required to confirm this result.

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