Quantiles naïve, ratio and difference estimators for efficient stratified sampling designs

Rochani Haresh,Samawi Hani,Zhang Xinyan 한국통계학회 2022 Journal of the Korean Statistical Society Vol.51 No.2

This paper proposes and investigates the bivariate, the marginal distribution functions and quantiles estimators and their asymptotic properties for naïve, ratio, and diference estimators based on the bivariate stratifed simple random sampling (BVSSRS) and bivariate stratifed ranked set sampling designs (BVSRSS). We demonstrate that the proposed estimators using BVSRSS and BVSSRS are consistent and asymptotically normally distributed. Improved performance of the proposed estimators using BVSRSS compared to BVSSRS supported through an intensive simulation study. The derivation of the optimal allocation based on BVSSRS and BVSRSS is provided. The National Health and Nutrition Examination Survey (NHANES) data is used to illustrate the methods.

On inference of multivariate means under ranked set sampling

Rochani, Haresh,Linder, Daniel F.,Samawi, Hani,Panchal, Viral The Korean Statistical Society 2018 Communications for statistical applications and me Vol.25 No.1

In many studies, a researcher attempts to describe a population where units are measured for multiple outcomes, or responses. In this paper, we present an efficient procedure based on ranked set sampling to estimate and perform hypothesis testing on a multivariate mean. The method is based on ranking on an auxiliary covariate, which is assumed to be correlated with the multivariate response, in order to improve the efficiency of the estimation. We showed that the proposed estimators developed under this sampling scheme are unbiased, have smaller variance in the multivariate sense, and are asymptotically Gaussian. We also demonstrated that the efficiency of multivariate regression estimator can be improved by using Ranked set sampling. A bootstrap routine is developed in the statistical software R to perform inference when the sample size is small. We use a simulation study to investigate the performance of the method under known conditions and apply the method to the biomarker data collected in China Health and Nutrition Survey (CHNS 2009) data.

Atypical depression: a comprehensive review.

Pae, Chi-Un,Tharwani, Haresh,Marks, David M,Masand, Prakash S,Patkar, Ashwin A Adis International 2009 CNS drugs Vol.23 No.12

<P>Despite several decades of research, the characteristics distinguishing atypical depression from other depressive subtypes remain ambiguous. Multiple lines of evidence support the designation of atypical depression as a scientifically and clinically relevant subtype, including differences in hormonal responses, brain laterality, psychological profile and psychiatric co-morbidity and differential treatment response. The evolution of the diagnostic criteria for atypical depression has led to the designation of mood reactivity as the cardinal feature, and the research supporting this conclusion is reviewed. This paper also reviews the evidence for the drug treatment of atypical depression, with a particular focus on research related to the superior efficacy of monoamine oxidase inhibitors (MAOIs) compared with tricyclic antidepressants (TCAs). Data relevant to the efficacy of newer antidepressants, including selective serotonin reuptake inhibitors (SSRIs), serotonin-noradrenaline (norepinephrine) reuptake inhibitors, transdermal selegiline and other new agents for atypical depression, are discussed. In summary, the diagnostic reliability and validity of atypical depression still remain elusive and open to further evolution. Currently available findings suggest that atypical depression has preferential response to MAOIs over TCAs. More data are required to determine the efficacy of newer agents relative to MAOIs and TCAs, although limited studies have shown a non-inferior efficacy and better tolerability of newer agents such as SSRIs compared with those of MAOIs and TCAs. Finally, future directions for research include further refinement of the diagnostic criteria for atypical depression, and clarification of the role of newer antidepressants in the treatment of this subtype with evidence from randomized, controlled trials.</P>

Slide Session : OS-END-38 ; Endocrinology : Awareness of Vitamin D Defi ciency Among Medical Doctors

( Yan Qin ),( Kok Seng Wong ),( Haresh Tulsidas ) 대한내과학회 2014 대한내과학회 추계학술대회 Vol.2014 No.1

Background: Vitamin D deficiency is a well-known under-diagnosed condition that is seeing a growing prevalence globally. It can lead to osteomalacia with diffuse bone and joint pain, muscle weakness, and difficulty walking. It is also associated with osteoporosis, increased risk of falls and fractures with little or no trauma especially among elderly. However it is not cost effective to screen everyone without adequate sun exposure for vitamin D deficiency. We conducted a study to determine the awareness of vitamin D deficiency among medical doctors. Methods: A cross-sectional survey using a piloted questionnaire was conducted among medical doctors in Internal Medicine department in our institution. It consisted of 5 questions: laboratory definition and symptoms of vitamin D deficiency, prevalence of vitamin D deficiency among adult Singaporeans, recommended daily vitamin D doses for adults who do not have adequate sun exposure and advice to patients on the sources of vitamin D acquisition. Results: A total of 59 (52.2% of 113 doctors of the department) doctors comprising 9 consultants, 5 registrars and 45 residents/medical officers/house officers responded. 47% (28) of doctors were aware of the laboratory definition of vitamin D deficiency, 63% (37) and 68% (40) were familiar with symptoms and prevalence respectively, majority 92% (54) would advise patients to acquire adequate vitamin D through sunlight, diet and dietary supplements. However, only 25% (15) were aware of the recommended daily dose. Conclusions: The awareness of vitamin D deficiency among Internal Medicine doctors who are the major medical care providers to Geriatric patients in our institution remained suboptimal. Periodic education through case studies or literature review of such topic especially to junior doctors is necessary. We believe that recognizing and treating vitamin D deficiency especially among elderly will have a great impact on healthcare policy decision and resource utilization.

Estimation of P(X > Y) when X and Y are dependent random variables using different bivariate sampling schemes

Samawi, Hani M.,Helu, Amal,Rochani, Haresh D.,Yin, Jingjing,Linder, Daniel The Korean Statistical Society 2016 Communications for statistical applications and me Vol.23 No.5

The stress-strength models have been intensively investigated in the literature in regards of estimating the reliability ${\theta}$ = P(X > Y) using parametric and nonparametric approaches under different sampling schemes when X and Y are independent random variables. In this paper, we consider the problem of estimating ${\theta}$ when (X, Y) are dependent random variables with a bivariate underlying distribution. The empirical and kernel estimates of ${\theta}$ = P(X > Y), based on bivariate ranked set sampling (BVRSS) are considered, when (X, Y) are paired dependent continuous random variables. The estimators obtained are compared to their counterpart, bivariate simple random sampling (BVSRS), via the bias and mean square error (MSE). We demonstrate that the suggested estimators based on BVRSS are more efficient than those based on BVSRS. A simulation study is conducted to gain insight into the performance of the proposed estimators. A real data example is provided to illustrate the process.

Kernel density estimation based on progressive type-II censoring

Helu Amal,Samawi Hani,Rochani Haresh,Yin Jingjing,Vogel Robert 한국통계학회 2020 Journal of the Korean Statistical Society Vol.49 No.2

Progressive censoring is essential for researchers in industry as a mean to remove subjects before the final termination point in order to save time and reduce cost. Recently, kernel density estimation has been intensively investigated due to its asymptotic properties and applications. In this paper, we investigate the asymptotic properties of the kernel density estimators based on progressive type-II censoring and their application to hazard function estimation. A bias-adjusted kernel density estimator is also proposed. Our simulation indicates that the kernel density estimates under progressive type-II censoring is competitive compared with kernel density estimates under simple random sampling, depending on the censoring schemes. An example regarding failure times of aircraft windshields is used to illustrate the proposed methods.

Hematologic Toxicity in Patients Undergoing Radical Anti-cancer Therapy: A Cross-Sectional Analysis of Patients in an Oncology Ward in India

Roy, Soumyajit,Mallick, Supriya,Raza, Md. Waseem,Haresh, Kunhi Parambath,Gupta, Subhash,Sharma, Daya Nand,Julka, Pramod Kumar,Rath, Goura Kisore Asian Pacific Journal of Cancer Prevention 2014 Asian Pacific journal of cancer prevention Vol.15 No.8

Burden of cancer is progressively increasing in developing countries like India which has also led to a steep rise in toxicity due to anti-cancer therapy. A cross-sectional analysis was here conducted for patients with different malignancies (except leukaemia) who while undergoing radical anti-cancer therapy were admitted to our oncology ward from January-July 2013. In a total of 280 patients, the total number of toxicity events was 473. Nine patients expired over this time period. Among the events, grade 2 anaemia the most common (n=189) while the most common grades of neutropenia and thrombocytopenia were grade 4 (n=114) and grade 2 (n=48), respectively. Among the tracable microbial etiologies, gram negative bacteria were the most commonly found pathogens. Treatment interruptions took place in 240 patients (median duration=8.8 days). Prolonged hospital admission, intensive care and artificial ventilation support was needed to be given in 48, 7 and 13 patients respectively. Advanced NSCLC, KPS <70, pancytopenia and artificial ventilation requirement were found to have a significant impact on death. Such studies show the prevailing practice from institutes of our country and may guide us formulating a guideline for managing such toxicities for this part of the world.

Steady State Analytical Model of a “Time Shared Li-ion Cell Blancing Circuit” for Plug-in Hybrid Vehicles and Utility Energy Storage

Abusaleh M. Imtiaz,Faisal H. Khan,Haresh Kamath 전력전자학회 2011 ICPE(ISPE)논문집 Vol.2011 No.5

A steady-state analytical model of the recently proposed “Time shared li-ion cell balancing circuit” is presented in this paper. This paper provides the necessary analytical proof of the cell balancer circuit to be used in future Plug-in Hybrid vehicles (PHEV) or utility energy storage applications. The model presented here bridges the simulation and experimental results obtained previously. In addition, the prototype of a four-cell lithium-ion battery balancer circuit with reduced component count has been constructed, and the test results have been verified with the analytical model. Although the “proof of concept” circuit was built to balance only four cells, the analytical model suggests that any number of series connected cells could be used in a string and balanced. Moreover, the analytical model can be extended to characterize the circuit parameters for any number of cells without any apparent issues. This model was also being verified using the simulation and experimental results with only 2% error margin.

Using ranked auxiliary covariate as a more efficient sampling design for ANCOVA model: analysis of a psychological intervention to buttress resilience

Jabrah, Rajai,Samawi, Hani M.,Vogel, Robert,Rochani, Haresh D.,Linder, Daniel F.,Klibert, Jeff The Korean Statistical Society 2017 Communications for statistical applications and me Vol.24 No.3

Drawing a sample can be costly or time consuming in some studies. However, it may be possible to rank the sampling units according to some baseline auxiliary covariates, which are easily obtainable, and/or cost efficient. Ranked set sampling (RSS) is a method to achieve this goal. In this paper, we propose a modified approach of the RSS method to allocate units into an experimental study that compares L groups. Computer simulation estimates the empirical nominal values and the empirical power values for the test procedure of comparing L different groups using modified RSS based on the regression approach in analysis of covariance (ANCOVA) models. A comparison to simple random sampling (SRS) is made to demonstrate efficiency. The results indicate that the required sample sizes for a given precision are smaller under RSS than under SRS. The modified RSS protocol was applied to an experimental study. The experimental study was designed to obtain a better understanding of the pathways by which positive experiences (i.e., goal completion) contribute to higher levels of happiness, well-being, and life satisfaction. The use of the RSS method resulted in a cost reduction associated with smaller sample size without losing the precision of the analysis.

Quality of Life of Patients with Advanced Cervical Cancer before and after Chemo-radiotherapy

Dahiya, Neha,Acharya, Anita S,Bachani, Damodar,Sharma, DN,Gupta, Subhash,Haresh, KP,Rath, GK Asian Pacific Journal of Cancer Prevention 2016 Asian Pacific journal of cancer prevention Vol.17 No.7

Background: Cervical cancer is the most frequently diagnosed cancer among women in India. Understanding quality of life (QOL) in women undergoing chemo-radiotherapy for cervical cancer will help in introducing interventions for better care and outcomes in these women. This study assessed QOL before and after chemo-radiotherapy in cervical cancer patients. Materials and Methods: This follow-up study covered sixty-seven newly diagnosed women with advanced cervical cancer (stages 2b to 4b). Structured questionnaires (the European Organization for Research and Treatment of Cancer, EORTC QLQ-C30 and EORTC QLQ-CX24) were used to assess the change in QOL after 6 months of treatment. Results: The mean age of women at the time of detection of cervical cancer was $52.3{\pm}11.29$ years (Range 30-75 years). Six months survival was 92.53%. The mean global health score of cervical cancer patients after six months of treatment was 59.52, which was significantly higher than the pre-treatment score of 50.15 (p=0.00007). Physical, cognitive and emotional functioning improved significantly (p<0.05) after treatment. Fatigue, pain, insomnia and appetite loss improved but episodes of diarrhea increased after treatment. The mean "symptoms score" using EORTC QLQ-CX24 post treatment was 20.0 which was significantly lower as compared to the pre- treatment score 30.0 (p<0.00001). Sexual enjoyment and sexual functioning decreased significantly after treatment. Conclusions: QOL of newly diagnosed cervical cancer patients improved significantly following chemo-radio therapy. Enhancement was also demonstrated on three of the five functional scales of EORTC QLQ-C30. To further improve QOL, interventions focusing on social and psychological support and physical rehabilitation may be needed.