scholarly journals Testing Equality of Treatments under an Incomplete Block Crossover Design with Ordinal Responses

2017 ◽  
Vol 13 (1) ◽  
Author(s):  
Kung-Jong Lui
Keyword(s):  
Ordinal Data ◽  
Crossover Trial ◽  
Crossover Design ◽  
Incomplete Block ◽  
Finite Sample ◽  
Test Procedures ◽  
Advantages And Disadvantages ◽  
Relative Treatment Effect ◽  
Patient Responses ◽  
High Doses

AbstractThe generalized odds ratio (GOR) for paired sample is considered to measure the relative treatment effect on patient responses in ordinal data. Under a three-treatment two-period incomplete block crossover design, both asymptotic and exact procedures are developed for testing equality between treatments with ordinal responses. Monte Carlo simulation is employed to evaluate and compare the finite-sample performance of these test procedures. A discussion on advantages and disadvantages of the proposed test procedures based on the GOR versus those based on Wald’s tests under the normal random effects proportional odds model is provided. The data taken as a part of a crossover trial studying the effects of low and high doses of an analgesic versus a placebo for the relief of pain in primary dysmenorrhea over the first two periods are applied to illustrate the use of these test procedures.

Exact tests in binary data under an incomplete block crossover design

2016 ◽  
Vol 27 (2) ◽  
pp. 579-592 ◽  
Author(s):  
Kung-Jong Lui ◽  
Kuang-Chao Chang
Keyword(s):  
Binary Data ◽  
Logistic Regression Model ◽  
Crossover Trial ◽  
Test Procedure ◽  
Crossover Design ◽  
Incomplete Block ◽  
Primary Dysmenorrhea ◽  
Test Procedures ◽  
Exact Test ◽  
High Doses

To improve the power of a parallel groups design and reduce the time length of a crossover trial, we may consider an incomplete block crossover design. Under a distribution-free random effects logistic regression model, we derive an exact test and a Mantel-Haenszel Type of summary test procedure for testing non-equality in binary data when comparing three treatments. We employ Monte Carlo simulation to evaluate the performance of these test procedures. We find that both test procedures developed here can perform well in a variety of situations. We use the data taken as a part of the crossover trial comparing the low and high doses of an analgesic with a placebo for the relief of pain in primary dysmenorrhea to illustrate the use of the proposed test procedures.

Testing equality and interval estimation of the generalized odds ratio in ordinal data under a three-period crossover design

2015 ◽  
Vol 26 (3) ◽  
pp. 1165-1181 ◽  
Author(s):  
Kung-Jong Lui ◽  
Kuang-Chao Chang ◽  
Chii-Dean Lin
Keyword(s):  
Odds Ratio ◽  
Ordinal Data ◽  
Interval Estimation ◽  
Crossover Design ◽  
Test Procedures ◽  
Exact Test ◽  
Number Of Patients ◽  
Interval Estimators ◽  
High Doses ◽  
Stratified Analysis

The crossover design can be of use to save the number of patients or improve power of a parallel groups design in studying treatments to noncurable chronic diseases. We propose using the generalized odds ratio for paired sample data to measure the relative effects in ordinal data between treatments and between periods. We show that one can apply the commonly used asymptotic and exact test procedures for stratified analysis in epidemiology to test non-equality of treatments in ordinal data, as well as obtain asymptotic and exact interval estimators for the generalized odds ratio under a three-period crossover design. We further show that one can apply procedures for testing the homogeneity of the odds ratio under stratified sampling to examine whether there are treatment-by-period interactions. We use the data taken from a three-period crossover trial studying the effects of low and high doses of an analgesic versus a placebo for the relief of pain in primary dysmenorrhea to illustrate the use of these test procedures and estimators proposed here.

scholarly journals Decitabine: A Historical Review of the Development Process of an Epigenetic Drug

2020 ◽  
Vol 7 ◽  
Author(s):  
Cihan Zamur ◽  
Uğur Topal
Keyword(s):  
Development Process ◽  
Historical Review ◽  
Low Doses ◽  
Combination Therapies ◽  
Action Mechanism ◽  
Epigenetic Effect ◽  
Epigenetic Drug ◽  
Patient Responses ◽  
High Doses

Decitabine (5-aza-2p-deoxycytidine) is a hypomethylation agent with a double-action mechanism, these are the reactivation of silenced genes; exhibiting differentiation at low doses and showing cytotoxicity at high doses. Decitabine was used as a classic anticancer drug in the original studies in the 1980s, 1500 to 2500 mg/m2 per cycle was the maximum clinically tolerated dose. The dosage was reassessed after a better understanding of epigenetics in cancer and the role of decitabine in epigenetic (hypomethylation) therapy was obtained, in about 1/20th of the previous doses (i.e., 'optimal biological' doses modulating hypomethylation). It has been found that decitabine (100 to 150 mg / m2 per cycle) can be used in patients with myelodysplastic syndromes (MDS) and other myeloid tumors, with manageable side effects. Combination therapies which amplify the epigenetic effect of decitabine will most likely improve the patient responses and allow it to be used in the treatment of other malignancies.

Near Observational Equivalence and Theoretical size Problems with Unit Root Tests

1996 ◽  
Vol 12 (4) ◽  
pp. 724-731 ◽  
Author(s):  
Jon Faust
Keyword(s):  
Unit Root ◽  
Sufficient Conditions ◽  
Unit Root Test ◽  
Asymptotic Distributions ◽  
Unit Root Tests ◽  
Finite Sample ◽  
Test Procedures ◽  
Asymptotic Size ◽  
Finite Sample Size ◽  
Topological Sense

Said and Dickey (1984,Biometrika71, 599–608) and Phillips and Perron (1988,Biometrika75, 335–346) have derived unit root tests that have asymptotic distributions free of nuisance parameters under very general maintained models. Under models as general as those assumed by these authors, the size of the unit root test procedures will converge to one, not the size under the asymptotic distribution. Solving this problem requires restricting attention to a model that is small, in a topological sense, relative to the original. Sufficient conditions for solving the asymptotic size problem yield some suggestions for improving finite-sample size performance of standard tests.

An Experimental Study of Longitudinal Tire Relaxation Constants for Vehicle Traction Dynamics Modeling

2019 ◽  
Author(s):  
Vladimir V. Vantsevich ◽  
Lyubomyr I. Demkiv ◽  
Sviatoslav R. Klos ◽  
Samuel R. Misko ◽  
Lee Moradi
Keyword(s):  
Experimental Study ◽  
Dynamic Models ◽  
Testing Machine ◽  
Transient Dynamics ◽  
Dynamics Modeling ◽  
Test Procedures ◽  
Advantages And Disadvantages ◽  
Frequency Domains ◽  
Tire Testing ◽  
Relaxation Characteristics

Abstract Existing literature on vehicle traction dynamics were reviewed for a variety of vehicle and tire dynamic models, some of which consider the pneumatic tires’ relaxation as a property of vehicle transient dynamics. In general, unlike the lateral relaxation counterpart, the longitudinal tire relaxation characteristics were mostly overlooked in tire transient dynamics modeling. As a continuation of the analytical study published in the 2018 DSCC Proceedings, the co-authors of this paper present an experimental study of the longitudinal tire relaxation characteristics of a Continental MPT 81 tire. Experimental results were obtained by conducting tests on an MTS Flat-Trac LTR tire testing machine. The experimental data is analyzed to investigate longitudinal tire relaxation characteristics as they relate to changes of tire conditions. The goal is to verify and refine the existing models suggested in the literature; as well as, discuss advantages and disadvantages of different test procedures and tire testing equipment. In particular, the paper investigates the longitudinal tire relaxation constant variation due to changes of wheel velocity, tire inflation pressure, and sine oscillations of tire slippage in the time and frequency domains. The paper concludes on the influence of the longitudinal tire relaxation constants on the tire/vehicle traction dynamics modeling.

scholarly journals Unified Least Squares Methods for the Evaluation of Diagnostic Tests With the Gold Standard

2017 ◽  
Vol 16 ◽  
pp. 117693511668606 ◽  
Author(s):  
Liansheng Larry Tang ◽  
Ao Yuan ◽  
John Collins ◽  
Xuan Che ◽  
Leighton Chan
Keyword(s):  
Least Squares ◽  
Diagnostic Tests ◽  
Ordinal Data ◽  
Least Squares Method ◽  
Test Results ◽  
Finite Sample ◽  
Monotonic Transformation ◽  
Model Framework ◽  
Response Variable ◽  
Continuous Test

The article proposes a unified least squares method to estimate the receiver operating characteristic (ROC) parameters for continuous and ordinal diagnostic tests, such as cancer biomarkers. The method is based on a linear model framework using the empirically estimated sensitivities and specificities as input “data.” It gives consistent estimates for regression and accuracy parameters when the underlying continuous test results are normally distributed after some monotonic transformation. The key difference between the proposed method and the method of Tang and Zhou lies in the response variable. The response variable in the latter is transformed empirical ROC curves at different thresholds. It takes on many values for continuous test results, but few values for ordinal test results. The limited number of values for the response variable makes it impractical for ordinal data. However, the response variable in the proposed method takes on many more distinct values so that the method yields valid estimates for ordinal data. Extensive simulation studies are conducted to investigate and compare the finite sample performance of the proposed method with an existing method, and the method is then used to analyze 2 real cancer diagnostic example as an illustration.

scholarly journals Ozone and Photocatalytic Processes for Pathogens Removal from Water: A Review

Catalysts ◽  
2019 ◽  
Vol 9 (1) ◽  
pp. 46 ◽  
Author(s):  
João Gomes ◽  
Ana Matos ◽  
Marta Gmurek ◽  
Rosa M. Quinta-Ferreira ◽  
Rui C. Martins
Keyword(s):  
Municipal Wastewater ◽  
Wastewater Treatment Plants ◽  
Antibiotic Resistance Genes ◽  
Cost Effective ◽  
Municipal Wastewater Treatment ◽  
Treated Water ◽  
Advantages And Disadvantages ◽  
Alternative Water ◽  
Municipal Wastewater Treatment Plants ◽  
High Doses

The search for alternative water sources is pushing to the reuse of treated water coming from municipal wastewater treatment plants. However, this requires that tightened standards be fulfilled. Among them is the microbiological safety of reused water. Although chlorination is the mostly applied disinfection system, it presents several disadvantages, such as the high doses required and the possibility of formation of dangerous by-products. Moreover, the threat of antibiotic resistance genes (ARGs) spread throughout poorly treated water is requiring the implementation of more efficient disinfection systems. Ozone and photo assisted disinfection technologies are being given special attention to reach treated water with higher quality. Still, much must be done to optimize the processes so that cost-effective systems may be obtained. This review paper gives a critical overview on the application of ozone and photo-based disinfection systems, bearing in mind their advantages and disadvantages when applied to water and municipal wastewater. Also, the possibility of integrated disinfection systems is considered.

Sign in / Sign up

Export Citation Format

Share Document