scholarly journals Exact Tests of Zero Variance Component in Presence of Multiple Variance Components with Application to Longitudinal Microbiome Study

2018 ◽  
Author(s):  
Jing Zhai ◽  
Kenneth Knox ◽  
Homer L. Twigg ◽  
Hua Zhou ◽  
Jin J. Zhou
Keyword(s):  
Likelihood Ratio ◽  
Likelihood Ratio Test ◽  
Variance Components ◽  
Null Hypothesis ◽  
Variance Component ◽  
Ratio Test ◽  
Type I ◽  
Exact Tests ◽  
Sample Sizes ◽  
Microbiome Composition

SummaryIn the metagenomics studies, testing the association of microbiome composition and clinical conditions translates to testing the nullity of variance components. Computationally efficient score tests have been the major tools. But they can only apply to the null hypothesis with a single variance component and when sample sizes are large. Therefore, they are not applicable to longitudinal microbiome studies. In this paper, we propose exact tests (score test, likelihood ratio test, and restricted likelihood ratio test) to solve the problems of (1) testing the association of the overall microbiome composition in a longitudinal design and (2) detecting the association of one specific microbiome cluster while adjusting for the effects from related clusters. Our approach combines the exact tests for null hypothesis with a single variance component with a strategy of reducing multiple variance components to a single one. Simulation studies demonstrate that our method has correct type I error rate and superior power compared to existing methods at small sample sizes and weak signals. Finally, we apply our method to a longitudinal pulmonary microbiome study of human immunodeficiency virus (HIV) infected patients and reveal two interesting genera Prevotella and Veillonella associated with forced vital capacity. Our findings shed lights on the impact of lung microbiome to HIV complexities. The method is implemented in the open source, high-performance computing language Julia and is freely available at https://github.com/JingZhai63/VCmicrobiome.

scholarly journals Likelihood ratio test between two groups of castor oil plant traits

2016 ◽  
Vol 46 (7) ◽  
pp. 1158-1164
Author(s):  
Betania Brum ◽  
Sidinei José Lopes ◽  
Daniel Furtado Ferreira ◽  
Lindolfo Storck ◽  
Alberto Cargnelutti Filho
Keyword(s):  
Likelihood Ratio ◽  
Likelihood Ratio Test ◽  
Type I Error ◽  
Plant Traits ◽  
Small Sample ◽  
Ratio Test ◽  
Type I ◽  
Sample Sizes ◽  
Oil Plant ◽  
Small Sample Sizes

ABSTRACT: The likelihood ratio test (LRT), to the independence between two sets of variables, allows to identify whether there is a dependency relationship between them. The aim of this study was to calculate the type I error and power of the LRT for determining independence between two sets of variables under multivariate normal distributions in scenarios consisting of combinations of 16 sample sizes; 40 combinations of the number of variables of the two groups; and nine degrees of correlation between the variables (for the power). The rate of type I error and power were calculate at 640 and 5,760 scenarios, respectively. A performance evaluation of the LRT was conducted by computer simulation by the Monte Carlo method, using 2,000 simulations in each scenario. When the number of variables was large (24), the TRV controlled the rate of type I errors and showed high power in sizes greater than 100 samples. For small sample sizes (25, 30 and 50), the test showed good performance because the number of variables did not exceed 12.

scholarly journals A Likelihood Ratio Test For The Homogeneity of Between-Study Variance in Network Meta-Analysis

2021 ◽  
Author(s):  
Dapeng Hu ◽  
Chong Wang ◽  
Annette O'Connor
Keyword(s):  
Likelihood Ratio ◽  
Likelihood Ratio Test ◽  
Random Effects ◽  
Type I Error ◽  
Meta Analysis ◽  
Indirect Evidence ◽  
Point Estimate ◽  
Ratio Test ◽  
Type I ◽  
Statistical Heterogeneity

Abstract Background: Network meta-analysis (NMA) is a statistical method used to combine results from several clinical trials and simultaneously compare multiple treatments using direct and indirect evidence. Statistical heterogeneity is a characteristic describing the variability in the intervention effects being evaluated in the different studies in network meta-analysis. One approach to dealing with statistical heterogeneity is to perform a random effects network meta-analysis that incorporates a between-study variance into the statistical model. A common assumption in the random effects model for network meta-analysis is the homogeneity of between-study variance across all interventions. However, there are applications of NMA where the single between-study assumption is potentially incorrect and instead the model should incorporate more than one between-study variances. Methods: In this paper, we develop an approach to testing the homogeneity of between-study variance assumption based on a likelihood ratio test. A simulation study was conducted to assess the type I error and power of the proposed test. This method is then applied to a network meta-analysis of antibiotic treatments for Bovine respiratory disease (BRD). Results: The type I error rate was well controlled in the Monte Carlo simulation. The homogeneous between-study variance assumption is unrealistic both statistically and practically in the network meta-analysis BRD. The point estimate and conffdence interval of relative effect sizes are strongly inuenced by this assumption. Conclusions: Since homogeneous between-study variance assumption is a strong assumption, it is crucial to test the validity of this assumption before conducting a network meta-analysis. Here we propose and validate a method for testing this single between-study variance assumption which is widely used for many NMA.

A global test for competing risks survival analysis

2020 ◽  
Vol 29 (12) ◽  
pp. 3666-3683
Author(s):  
Dominic Edelmann ◽  
Maral Saadati ◽  
Hein Putter ◽  
Jelle Goeman
Keyword(s):  
Survival Analysis ◽  
Likelihood Ratio ◽  
Likelihood Ratio Test ◽  
Competing Risks ◽  
Cox Model ◽  
Wald Test ◽  
Ratio Test ◽  
Type I ◽  
Multistate Models ◽  
Global Test

Standard tests for the Cox model, such as the likelihood ratio test or the Wald test, do not perform well in situations, where the number of covariates is substantially higher than the number of observed events. This issue is perpetuated in competing risks settings, where the number of observed occurrences for each event type is usually rather small. Yet, appropriate testing methodology for competing risks survival analysis with few events per variable is missing. In this article, we show how to extend the global test for survival by Goeman et al. to competing risks and multistate models[Per journal style, abstracts should not have reference citations. Therefore, can you kindly delete this reference citation.]. Conducting detailed simulation studies, we show that both for type I error control and for power, the novel test outperforms the likelihood ratio test and the Wald test based on the cause-specific hazards model in settings where the number of events is small compared to the number of covariates. The benefit of the global tests for competing risks survival analysis and multistate models is further demonstrated in real data examples of cancer patients from the European Society for Blood and Marrow Transplantation.

Improved Tests for an Ordered Hypothesis in one Parameter Exponential Families

1993 ◽  
Vol 43 (1-2) ◽  
pp. 57-64
Author(s):  
Teng Li
Keyword(s):  
Likelihood Ratio ◽  
Likelihood Ratio Test ◽  
Null Hypothesis ◽  
Alternative Hypothesis ◽  
Subject Classification ◽  
Exponential Families ◽  
Ratio Test ◽  
Primary 62F03 ◽  
Special Cases

We consider m independent one parameter exponential families with parameters (θ1, θ2,  , θ m), and the alternative hypothesis [Formula: see text] where [Formula: see text] are specified. The null hypothesis Ho is the complement of H1. A class of tests more powerful than the likelihood ratio test (LRT) is derived. Applications to two special cases, Binomial and Poisson, are indicated. AMS 1980 Subject Classification: Primary 62F03

scholarly journals Testing the Robustness of the Likelihood-Ratio Test in a Variance-Component Quantitative-Trait Loci–Mapping Procedure

1999 ◽  
Vol 65 (2) ◽  
pp. 531-544 ◽  
Author(s):  
David B. Allison ◽  
Michael C. Neale ◽  
Raffaella Zannolli ◽  
Nicholas J. Schork ◽  
Christopher I. Amos ◽  
...  
Keyword(s):  
Quantitative Trait Loci ◽  
Likelihood Ratio ◽  
Likelihood Ratio Test ◽  
Quantitative Trait ◽  
Variance Component ◽  
Ratio Test ◽  
Quantitative Trait Loci Mapping ◽  
Mapping Procedure ◽  
Trait Loci

scholarly journals On the use of linear regression and maximum likelihood for QTL mapping in half-sib designs

1998 ◽  
Vol 72 (2) ◽  
pp. 149-158 ◽  
Author(s):  
P. V. BARET ◽  
S. A. KNOTT ◽  
P. M. VISSCHER
Keyword(s):  
Maximum Likelihood ◽  
Linear Regression ◽  
Likelihood Ratio ◽  
Likelihood Ratio Test ◽  
Null Hypothesis ◽  
Alternative Hypothesis ◽  
Ratio Test ◽  
Test Statistics ◽  
Daughter Design ◽  
Practical Implications

Methods of identification of quantitative trait loci (QTL) using a half-sib design are generally based on least-squares or maximum likelihood approaches. These methods differ in the genetical model considered and in the information used. Despite these differences, the power of the two methods in a daughter design is very similar. Using an analogy with a one-way analysis of variance, we propose an equation connecting the two test-statistics (F ratio for regression and likelihood ratio test in the case of the maximum likelihood). The robustness of this relationship is tested by simulation for different single QTL models. In general, the correspondence between the two statistics is good under both the null hypothesis and the alternative hypothesis of a single QTL segregating. Practical implications are discussed with particular emphasis on the theoretical distribution of the likelihood ratio test.

Homogeneity testing for binomial proportions under stratified double-sampling scheme with two fallible classifiers

2020 ◽  
Vol 29 (12) ◽  
pp. 3547-3568
Author(s):  
Shi-Fang Qiu ◽  
Qi-Xiang Fu
Keyword(s):  
Least Squares ◽  
Likelihood Ratio ◽  
Likelihood Ratio Test ◽  
Weighted Least Squares ◽  
Score Test ◽  
Double Sampling ◽  
Ratio Test ◽  
Sample Sizes ◽  
Log Transformation ◽  
Binomial Proportions

This article investigates the homogeneity testing problem of binomial proportions for stratified partially validated data obtained by double-sampling method with two fallible classifiers. Several test procedures, including the weighted-least-squares test with/without log-transformation, logit-transformation and double log-transformation, and likelihood ratio test and score test, are developed to test the homogeneity under two models, distinguished by conditional independence assumption of two classifiers. Simulation results show that score test performs better than other tests in the sense that the empirical size is generally controlled around the nominal level, and hence be recommended to practical applications. Other tests also perform well when both binomial proportions and sample sizes are not small. Approximate sample sizes based on score test, likelihood ratio test and the weighted-least-squares test with double log-transformation are generally accurate in terms of the empirical power and type I error rate with the estimated sample sizes, and hence be recommended. An example from the malaria study is illustrated by the proposed methodologies.

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