Simulated Annealing of Constrained Statistical Functions

In 1987, Corana et al. published a simulated annealing (SA) algorithm. Soon thereafter in 1993, Goffe et al. coded the algorithm in FORTRAN and showed that SA could uncover global optima missed by traditional optimization software when applied to statistical modeling and estimation in economics (econometrics). This chapter shows how and why SA can be used successfully to perform likelihood-based statistical inference on models where likelihood is constrained by often very complicated functions defined on a compact parameter space. These constraints arise because likelihood-based inference involves comparing the maxima of constrained versus unconstrained statistical optimization models. The chapter begins with a review of the relevant literature on SA and constrained optimization using penalty techniques. Next, a constrained optimization problem based in maximum likelihood stress-strength modeling is introduced, and its statistical and numerical properties are summarized. SA is then used to solve a sequence of penalty-constrained optimization problems, and the results are used to construct a confidence interval for the parameter of interest in the statistical model. The chapter concludes with a brief summary of the results and some ways we were able to enhance the performance of SA in this setting

Inference for the Sharpe Ratio Using a Likelihood-Based Approach

The Sharpe ratio is the prominent risk-adjusted performance measure used by practitioners. Statistical testing of this ratio using its asymptotic distribution has lagged behind its use. In this paper, highly accurate likelihood analysis is applied for inference on the Sharpe ratio. Both the one- and two-sample problems are considered. The methodology has O(n-3/2) distributional accuracy and can be implemented using any parametric return distribution structure. Simulations are provided to demonstrate the method\u27s superior accuracy over existing methods used for testing in the literature

The association of types of training and practice settings with doctors’ empathy and patient enablement among patients with chronic illness in Hong Kong

Background: The increase in non-communicable disease (NCD) is becoming a global health problem and there is an increasing need for primary care doctors to look after these patients although whether family doctors are adequately trained and prepared is unknown. Objective: This study aimed to determine if doctors with family medicine (FM) training are associated with enhanced empathy in consultation and enablement for patients with chronic illness as compared to doctors with internal medicine training or without any postgraduate training in different clinic settings. Methods: This was a cross-sectional questionnaire survey using the validated Chinese version of the Consultation and Relational Empathy (CARE) Measure as well as Patient Enablement Instrument (PEI) for evaluation of quality and outcome of care. 14 doctors from hospital specialist clinics (7 with family medicine training, and 7 with internal medicine training) and 13 doctors from primary care clinics (7 with family medicine training, and 6 without specialist training) were recruited. In total, they consulted 823 patients with chronic illness. The CARE Measure and PEI scores were compared amongst doctors in these clinics with different training background: family medicine training, internal medicine training and those without specialist training. Generalized estimation equation (GEE) was used to account for cluster effects of patients nested with doctors. <b>Results</b> Within similar clinic settings, FM trained doctors had higher CARE score than doctors with no FM training. In hospital clinics, the difference of the mean CARE score for doctors who had family medicine training (39.2, SD = 7.04) and internal medicine training (35.5, SD = 8.92) was statistically significant after adjusting for consultation time and gender of the patient. In the community care clinics, the mean CARE score for doctors with family medicine training and those without specialist training were 32.1 (SD = 7.95) and 29.2 (SD = 7.43) respectively, but the difference was not found to be significant. For PEI, patients receiving care from doctors in the hospital clinics scored significantly higher than those in the community clinics, but there was no significant difference in PEI between patients receiving care from doctors with different training backgrounds within similar clinic setting. Conclusion: Family medicine training was associated with higher patient perceived empathy for chronic illness patients in the hospital clinics. Patient enablement appeared to be associated with clinic settings but not doctors’ training background. Training in family medicine and a clinic environment that enables more patient doctor time might help in enhancing doctors’ empathy and enablement for chronic illness patients

How to Address Non-normality: A Taxonomy of Approaches, Reviewed, and Illustrated

The linear model often serves as a starting point for applying statistics in psychology. Often, formal training beyond the linear model is limited, creating a potential pedagogical gap because of the pervasiveness of data non-normality. We reviewed 61 recently published undergraduate and graduate textbooks on introductory statistics and the linear model, focusing on their treatment of non-normality. This review identified at least eight distinct methods suggested to address non-normality, which we organize into a new taxonomy according to whether the approach: (a) remains within the linear model, (b) changes the data, and (c) treats normality as informative or as a nuisance. Because textbook coverage of these methods was often cursory, and methodological papers introducing these approaches are usually inaccessible to non-statisticians, this review is designed to be the happy medium. We provide a relatively non-technical review of advanced methods which can address non-normality (and heteroscedasticity), thereby serving a starting point to promote best practice in the application of the linear model. We also present three empirical examples to highlight distinctions between these methods' motivations and results. The paper also reviews the current state of methodological research in addressing non-normality within the linear modeling framework. It is anticipated that our taxonomy will provide a useful overview and starting place for researchers interested in extending their knowledge in approaches developed to address non-normality from the perspective of the linear model

DEVELOPMENT AND PERFORMANCE OF THE PEPPER INDUSTRY IN MALAYSIA: A CRITICAL REVIEW

The National Commodity Policy 2011-2020 was developed to increase the national income by harnessing the potential of commodity export revenues. Despite continuous efforts implemented by various related agencies, the overall performance of major commodities, particularlypepper, remains unsatisfactory.Regarded as a sought-after ‘king of spices’, pepper has become one of the most prized and important commodities traded globally.This paper highlights the development and performance of the pepper industry in Malaysia and discusses practical strategies and recommendations to transform the pepper industry. Besides conducting interviews with the industry experts to gain first-hand information, content and thematic analysis was employed based on secondary data researchin this study. The findings of the study show that even though pepper is mostly used in food-related industries, its potential in pharmaceutical and cosmeceutical sectors remains underexplored. Globally, the overall supply and demand of pepper continue to increase, though the demand has recently exceeded supply. However, continuous new planting and farm expansion initiatives by major producers caused the total global pepper supply to exceed consumption in 2018. In fact, pepper prices have declined more than 70% since 2015, which affected the overall household income of the rural community engaged in pepper farming. While experiencing low prices, smallholder pepper farmers and the industry continue to struggle with low domestic consumption, low production, higher cost of farm inputs, lack of extension services, low impact of research, development and innovation, ageing farming population, intense competition from other producing countries, low prices for quality pepper, limited subsidy to support continuous farming, pepper-related diseases, lack of new technology, and poor investment in downstream activities. Given this, the performance of the Malaysian pepper industry has fallen below expectations

Primate survey in a Bornean flooded forest: evaluation of best approach and best timing

Accurate determination of the abundance and distribution of animals, particularly endangered species, is a fundamental requirement for understanding their ecology and has important applications for their conservation. In Bornean flooded forests, various approaches have previously been used to conduct primate census, including foot-based land surveys and boat-based river surveys at different times of the day such as in the early morning and/or late afternoon. However, the accuracy of primate encounter frequencies and animal counts obtained using these methods has not been assessed. Therefore, in this study, we attempted to assess the accuracy of these methods used in different studies. We found that boat-based river surveys were more accurate than foot-based land surveys for evaluating the abundance and distribution of Bornean primates, particularly proboscis monkeys (Nasalis larvatus) and long-tailed macaques (Macaca fascicularis). Furthermore, based on our evaluation of boat-based river surveys at different times of the day, we recommend that such surveys be performed in the late afternoon to yield more accurate estimates of the abundances and distributions of Bornean primates

Primate survey in a Bornean flooded forest: evaluation of best approach and best timing

Accurate determination of the abundance and distribution of animals, particularly endangered species, is a fundamental requirement for understanding their ecology and has important applications for their conservation. In Bornean flooded forests, various approaches have previously been used to conduct primate census, including foot-based land surveys and boat-based river surveys at different times of the day such as in the early morning and/or late afternoon. However, the accuracy of primate encounter frequencies and animal counts obtained using these methods has not been assessed. Therefore, in this study, we attempted to assess the accuracy of these methods used in different studies. We found that boat-based river surveys were more accurate than foot-based land surveys for evaluating the abundance and distribution of Bornean primates, particularly proboscis monkeys (Nasalis larvatus) and long-tailed macaques (Macaca fascicularis). Furthermore, based on our evaluation of boat-based river surveys at different times of the day, we recommend that such surveys be performed in the late afternoon to yield more accurate estimates of the abundances and distributions of Bornean primates

SARS Transmission among Hospital Workers in Hong Kong

Despite infection control measures, breakthrough transmission of severe acute respiratory syndrome (SARS) occurred for many hospital workers in Hong Kong. We conducted a case-control study of 72 hospital workers with SARS and 144 matched controls. Inconsistent use of goggles, gowns, gloves, and caps was associated with a higher risk for SARS infection (unadjusted odds ratio 2.42 to 20.54, p < 0.05). The likelihood of SARS infection was strongly associated with the amount of personal protection equipment perceived to be inadequate, having <2 hours of infection control training, and not understanding infection control procedures. No significant differences existed between the case and control groups in the proportion of workers who performed high-risk procedures, reported minor protection equipment problems, or had social contact with SARS-infected persons. Perceived inadequacy of personal protection equipment supply, infection control training <2 hours, and inconsistent use of personal protection equipment when in contact with SARS patients were significant independent risk factors for SARS infection

Assay of pleural fluid interleukin-6, tumour necrosis factor-alpha and interferon-gamma in the diagnosis and outcome correlation of tuberculous effusion

AbstractObjective: To assess the usefulness of interleukin-6 (IL-6), tumour necrosis factor-alpha (TNF-α) and interferon-gamma (IFN-γ) in the diagnosis and prediction of outcome of pleural tuberculosis.Patients and methods: Pleural fluid from 32 TB and 34 non-TB patients was sent for assay of IL-6, TNF-α and IFN-γ. Clinical parameters at presentation and residual pleural scarring at completion of treatment were assessed for pleural TB cases.Results: The pleural fluid levels of IL-6, TNF-α and IFN-γ in TB patients were significantly higher than those with non-TB effusions (P values of <0.001, 0.018 and <0.001, respectively by independent t-test). Utility of these cytokines for diagnosis of pleural TB was evaluated using receiver operating characteristic (ROC) curve analysis. The cut-off values for IL-6, TNF-α and IFN-γ determined in this analysis were 4000, 4 and 60pg/ml respectively, and their sensitivity and specificity were 90.6% and 76.5%, 90.6% and 79.4%, 100% and 100%, respectively. The pretreatment pleural fluid IL-6 levels had a positive correlation with the number of febrile days after treatment (Pearson correlation test: r=0.60, P=0.009). A negative correlation was found between the percentage reduction in pleural fluid cytokines after 2 weeks treatment and the extent of residual pleural scarring (IL-6: r=–0.62, P=0.041; TNF-α: r=–0.65, P=0.030; IFN-γ: r=–0.83, P=0.002).Conclusion: Pleural fluid IL-6, TNF-α and IFN-γ assays are useful in the diagnosis of pleural TB. The initial IL-6 level correlates with the number of febrile days. The percentage change of cytokines after 2 weeks of treatment also helps to predict residual pleural scarring

Use and awareness of and willingness to self-test for HIV: an analysis of cross-sectional population-based surveys in Malawi and Zimbabwe.

BACKGROUND: Many southern African countries are nearing the global goal of diagnosing 90% of people with HIV by 2020. In 2016, 84 and 86% of people with HIV knew their status in Malawi and Zimbabwe, respectively. However, gaps remain, particularly among men. We investigated awareness and use of, and willingness to self-test for HIV and explored sociodemographic associations before large-scale implementation. METHODS: We pooled responses from two of the first cross-sectional Demographic and Health Surveys to include HIV self-testing (HIVST) questions in Malawi and Zimbabwe in 2015-16. We investigated sociodemographic factors and sexual risk behaviours associated with previously testing for HIV, and past use, awareness of, and future willingness to self-test using univariable and multivariable logistic regression, adjusting for the sample design and limiting analysis to participants with a completed questionnaire and valid HIV test result. We restricted analysis of willingness to self-test to Zimbabwean men, as women and Malawians were not systematically asked this question. RESULTS: Of 31,385 individuals, 31.2% of men had never tested compared with 16.5% of women (p < 0.001). For men, the likelihood of having ever tested increased with age. Past use and awareness of HIVST was very low, 1.2 and 12.6%, respectively. Awareness was lower among women than men (9.1% vs 15.3%, adjusted odds ratio [aOR] = 1.55; 95% confidence interval [CI]: 1.37-1.75), and at younger ages, and lower education and literacy levels. Willingness to self-test among Zimbabwean men was high (84.5%), with greater willingness associated with having previously tested for HIV, being at high sexual risk (highest willingness [aOR = 3.74; 95%CI: 1.39-10.03, p < 0.009]), and being ≥25 years old. Wealthier men had greater awareness of HIVST than poorer men (p < 0.001). The highest willingness to self-test (aOR = 3.74; 95%CI: 1.39-10.03, p < 0.009) was among men at high HIV-related sexual risk. CONCLUSIONS: In 2015-16, many Malawian and Zimbabwean men had never tested for HIV. Despite low awareness and minimal HIVST experience, willingness to self-test was high among Zimbabwean men, especially older men with moderate-to-high HIV-related sexual risk. These data provide a valuable baseline against which to investigate population-level uptake of HIVST as programmes scale up. Programmes introducing, or planning to introduce, HIVST should consider including relevant questions in population-based surveys