scholarly journals Alternatives to Mixture Model Analysis of Correlated Binomial Data

2012 ◽  
Vol 2012 ◽  
pp. 1-10 ◽  
Author(s):  
N. Rao Chaganty ◽  
Roy Sabo ◽  
Yihao Deng
Keyword(s):  
Mixture Model ◽  
Linear Models ◽  
Mixture Distribution ◽  
Estimating Equation ◽  
Repeated Measure ◽  
Distribution Models ◽  
Binomial Data ◽  
Software Packages ◽  
Mixture Model Approach ◽  
Correlated Binomial

While univariate instances of binomial data are readily handled with generalized linear models, cases of multivariate or repeated measure binomial data are complicated by the possibility of correlated responses. Likelihood-based estimation can be applied by using mixture distribution models, though this approach can present computational challenges. The logistic transformation can be used to bypass these concerns and allow for alternative estimating procedures. One popular alternative is the generalized estimating equation (GEE) method, though systematic errors can lead to infeasible correlation estimates or nonconvergence problems. Our approach is the coupling of quasileast squares (QLSs) method with a rarely used matrix factorization, which achieves a simplified estimation platform—as compared to the mixture model approach—and does not suffer from the convergence problems in GEE method. A noncontrived example is provided that shows the mechanical breakdown of GEE using several statistical software packages and highlights the usefulness of the QLS approach.

Accounting for fish shoals in single- and multi-species survey data using mixture distribution models

2011 ◽  
Vol 68 (9) ◽  
pp. 1681-1693 ◽  
Author(s):  
James T. Thorson ◽  
Ian J. Stewart ◽  
André E. Punt
Keyword(s):  
Linear Models ◽  
Survey Design ◽  
Mixture Distribution ◽  
Trawl Survey ◽  
Distribution Models ◽  
Mixed Effects Modeling ◽  
Conventional Models ◽  
Catch Rates ◽  
Log Linear ◽  
Trawl Catches

A scientific bottom trawl survey targeting Pacific rockfishes (Sebastes spp.) occasionally yields extraordinary catch events (ECEs) in which catch-per-unit-area is much greater than usual. We hypothesize that ECEs result from trawl catches of fish shoals. We developed mixture distribution models for positive catch rates to identify spatial covariates associated with ECEs or normal trawl catches and used simulation modeling to contrast the performance of mixture distribution and conventional log-linear models for estimating an annual index of positive catch rates. Finally, mixed-effects modeling was applied to multispecies data to evaluate the hypothesis that ECEs are related to shoaling behaviors. Results show that mixture distribution models are often selected over conventional models for shoaling species and that untrawlable habitat has a positive effect on rockfish densities. Simulation shows that mixture distribution models can perform as well as or better than conventional models at predicting positive catch rates. Finally, model selection supports the hypothesis that shoaling behaviors contribute to the occurrence of ECEs. We propose that greater understanding of ECEs and shoaling habitat selection could be useful in future spatial management and survey design and that mixture distribution models could improve methods for estimating annual indices of abundance.

Efficacy and Tolerability of Lacosamide for Focal Epileptic Patients: Study from Epilepsy Clinic in Makkah

2020 ◽  
Vol 19 ◽  
Author(s):  
Amal Alkhotani ◽  
Hanadi Abualula ◽  
Yasir Almatrafi ◽  
Sawsan Ghoniem ◽  
Alaa Alkhotani
Keyword(s):  
Focal Epilepsy ◽  
Estimating Equation ◽  
Repeated Measure ◽  
Improvement Rate ◽  
Temporal Epilepsy ◽  
Voltage Gated Sodium Channels ◽  
Significant Difference ◽  
Epileptic Patients ◽  
Medical City ◽  
Seizure Rate

Background: Lacosamide characterized by a novel dual mode of action in its components, in which it has a func-tionalized amino acid that selectively pro, motes inactivation of voltage-gated sodium channels slowly among patients. Objective: To assess the effectiveness and tolerability of Lacosamide in the treatment of focal epileptic patients. Methods: This retrospective cohort study obtains data from the clinic notes or diaries of all patients during 2014 to 2019 from King Abdullah Medical City. The multivariate generalized estimating equation (GEE) repeated measure Logistic Re-gression Analysis was used to assess the change in patients’ odds of having an improvised seizure rate. Results: Majority of the focal epileptic patients were diagnosed with temporal epilepsy (57.9%), while 26.3% had frontal epileptic lesion/diagnoses. Majority of the patients (54.4%) had received a combination of old and new treatment. 57.14% of the seven patients had dizziness and headache, tremors (n = 1), loss of balance (n = 1) and increased seizure with abnormal vision acuity and psychosis (n = 1). 84.2% of the patients had reduction of their median seizure frequency at the 12-month period. However, there were no significant difference on the seizure control rate based on clinical characteristics. There were no statistically significant differences between male and female patients on their improvement rate across the four times on average. Conclusion: Lacosamide is an effective well tolerate drug for patients with focal epilepsy.

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