Methodological issues with adaptation of clinical trial design

Adaptation of clinical trial design generates many issues that have not been resolved for practical applications, though statistical methodology has advanced greatly. This paper focuses on some methodological issues. In one type of adaptation such as sample size re-estimation, only the postulated value of a parameter for planning the trial size may be altered. In another type, the originally intended hypothesis for testing may be modified using the internal data accumulated at an interim time of the trial, such as changing the primary endpoint and dropping a treatment arm. For sample size re-estimation, we make a contrast between an adaptive test weighting the two-stage test statistics with the statistical information given by the original design and the original sample mean test with a properly corrected critical value. We point out the difficulty in planning a confirmatory trial based on the crude information generated by exploratory trials. In regards to selecting a primary endpoint, we argue that the selection process that allows switching from one endpoint to the other with the internal data of the trial is not very likely to gain a power advantage over the simple process of selecting one from the two endpoints by testing them with an equal split of alpha (Bonferroni adjustment). For dropping a treatment arm, distributing the remaining sample size of the discontinued arm to other treatment arms can substantially improve the statistical power of identifying a superior treatment arm in the design. A common difficult methodological issue is that of how to select an adaptation rule in the trial planning stage. Pre-specification of the adaptation rule is important for the practicality consideration. Changing the originally intended hypothesis for testing with the internal data generates great concerns to clinical trial researchers.     

Weighting variables in Kohonen competitive learning algorithms

This paper presents a new variable weight method, called the singular value decomposition (SVD) approach, for Kohonen competitive learning (KCL) algorithms based on the concept of Varshavsky et al. [18 R. Varshavsky, A. Gottlieb, M. Linial, and D. Horn, Novel unsupervised feature filtering of bilogical data, Bioinformatics 22 (2006), pp. 507–513.[Crossref], [PubMed], [Web of Science ®] , [Google Scholar]]. Integrating the weighted fuzzy c-means (FCM) algorithm with KCL, in this paper, we propose a weighted fuzzy KCL (WFKCL) algorithm. The goal of the proposed WFKCL algorithm is to reduce the clustering error rate when data contain some noise variables. Compared with the k-means, FCM and KCL with existing variable-weight methods, the proposed WFKCL algorithm with the proposed SVD's weight method provides a better clustering performance based on the error rate criterion. Furthermore, the complexity of the proposed SVD's approach is less than Pal et al. [17 S.K. Pal, R.K. De, and J. Basak, Unsupervised feature evaluation: a neuro-fuzzy approach, IEEE. Trans. Neural Netw. 11 (2000), pp. 366–376.[Crossref], [PubMed], [Web of Science ®] , [Google Scholar]], Wang et al. [19 X.Z. Wang, Y.D. Wang, and L.J. Wang, Improving fuzzy c-means clustering based on feature-weight learning, Pattern Recognit. Lett. 25 (2004), pp. 1123–1132.[Crossref], [Web of Science ®] , [Google Scholar]] and Hung et al. [9 W. -L. Hung, M. -S. Yang, and D. -H. Chen, Bootstrapping approach to feature-weight selection in fuzzy c-means algorithms with an application in color image segmentation, Pattern Recognit. Lett. 29 (2008), pp. 1317–1325.[Crossref], [Web of Science ®] , [Google Scholar]].     

Does Asymmetry of International Shocks Matter for the U.S. Business Cycle?

This article proposes and investigates the asymmetry hypothesis, which predicts that an international asymmetric shock tends to have a stronger and longer effect on the U.S. business cycle than a symmetric shock. The hypothesis finds empirical support in the impulse responses of U.S. output and inflation to symmetric and asymmetric shocks; those responses are estimated in a four-variable structural vector autoregression. The hypothesis also finds support in stylized facts: The longest U.S. expansions have tended to occur when the rest of the world was growing below potential.     

Quality of Life of Poor People Living in Remote Areas in Hong Kong

Based on three surveys carried out for studying living conditions of youth, women and elderly living in six remote areas (Tuen Mun, Yuen Long, Tin Shui Wai, Sheung Shui, Fan Ling and Tai Po) in the New Territories of Hong Kong, this paper reports the poverty and social exclusion of these three groups of people. The quality of life of youth, women and elderly is adversely affected by limited job opportunities, high cost of travel for employment, and poor neighbourhoods in the community. However, perceptions of reasons for their problems are different for the three groups, due to differences in bonding and bridging social capital they have, as well as the differences in perceptions on social exclusion and discrimination directed upon them.     

Quality of Life in Older Adults: Benefits from Caring Services in Hong Kong

Many older adults are in need of care. Therefore, older people would generally benefit from the use of caring services, notably including home care, residential care, nursing, and medical services. The contributory factors underlying caring services tend to be a caring perspective that aspires to sustain older peoples social relationships and real-life involvement. To gauge the benefits from various social and health services, the present study relies on a large-scale survey of 3000 older adults in Hong Kong, using quality of life as a criterion. Results showed that an older adult who had used (ordinary or enhanced) home care services for a longer time turned out to have appreciably more improvement in quality of life. Besides, those who joined an interest group more frequently were higher in quality of life, including the health domain. On the other hand, frequent use of medical and meal-to-home services were signals that reflected problems detrimental to the older users quality of life. Despite this, the quality of clinics or hospitals, as perceived by the older adult, was the most beneficial. As such, caring services that foster older adults interests, cater to their health care needs, and embody quality can have principal contribution to their users quality of life.     

Exploring personhood in dining experiences of residents with dementia in long-term care facilities

Despite the shift toward using person-centered approaches in dementia care, the relevance and applicability of the concept “personhood” remains unclear in everyday practice and activities, such as mealtime experience for residents with dementia. Based on a qualitative study, this paper presents emergent themes at mealtimes that support or undermine personhood of twenty residents with dementia in two long-term care facilities. Methods of data collection included conversational interviews with residents with dementia, participant observations, focus groups with staff and examination of available documents. Data analysis identified eight themes: (1) outpacing/relaxed pace, (2) withholding/holding, (3) stimulation, (4) disrespect/respect, (5) invalidation/validation, (6) distancing/connecting, (7) disempowerment/empowerment, and (8) ignoring/inclusion. These findings raised questions about current practice and identified areas for improvement. Although staff approaches seemed to have the greatest impact on residents' experiences, the physical environment and organizational milieu were also responsible for hindering and facilitating staff to provide the best possible care and interaction.     

朝鲜燕行使与中国琉璃厂

朝鲜李朝的燕行使和中国明清时期的琉璃厂有着千丝万缕的联系。朝鲜好多名人学士回国后都在著述里留有琉璃厂的记录,而燕行使与中国学者在琉璃厂结下的深厚友谊也在当时和后世传为佳话,由此可以看出,燕行使与琉璃厂的结缘对朝鲜吸收先进文化起到了重要作用。     

Simultaneous prediction intervals for multiple comparisons with a standard

k normal populations having common variance are used to construct two-sided and one-sided simultaneous prediction intervals for the differences between the future means of independent random sample from each of these populations compared to a standard. These prediction intervals are particularly useful if one has sampled the performance of several products and wishes to simultaneously predict the differences between future sample mean performance of these products and a standard with a predetermined joint probability. Methods on sample size determination are also given. The procedures are illustrated with a numerical example. Received: February 25, 2000; revised version: February 6, 2001     

Measuring Attitudes About Intimate Partner Violence Against Women: The ATT-IPV Scale

In lower-income settings, women more often than men justify intimate partner violence (IPV). Yet, the role of measurement invariance across gender is unstudied. We developed the ATT-IPV scale to measure attitudes about physical violence against wives in 1,055 married men and women ages 18–50 in My Hao district, Vietnam. Across 10 items about transgressions of the wife, women more often than men agreed that a man had good reason to hit his wife (3 % to 92 %; 0 % to 67 %). In random split-half samples, one-factor exploratory factor analysis (EFA) (N ₁ = 527) and confirmatory factor analysis (CFA) (N ₂ = 528) models for nine items with sufficient variability had significant loadings (0.575–0.883; 0.502–0.897) and good fit (RMSEA = 0.068, 0.048; CFI = 0.951, 0.978, TLI = 0.935, 0.970). Three items had significant uniform differential item functioning (DIF) by gender, and adjustment for DIF revealed that measurement noninvariance was partially masking men’s lower propensity than women to justify IPV. A CFA model for the six items without DIF had excellent fit (RMSEA = 0.019, CFI = 0.994, TLI = 0.991) and an attitudinal gender gap similar to the DIF-adjusted nine-item model, suggesting that the six-item scale reliably measures attitudes about IPV across gender. Researchers should validate the scale in urban Vietnam and elsewhere and decompose DIF-adjusted gender attitudinal gaps.     

Estimation of the parameters of the Gompertz distribution under the first failure-censored sampling plan

This article presents the goodness-of-fit tests for the Laplace distribution based on its maximum entropy characterization result. The critical values of the test statistics estimated by Monte Carlo simulations are tabulated for various window and sample sizes. The test statistics use an entropy estimator depending on the window size; so, the choice of the optimal window size is an important problem. The window sizes for yielding the maximum power of the tests are given for selected sample sizes. Power studies are performed to compare the proposed tests with goodness-of-fit tests based on the empirical distribution function. Simulation results report that entropy-based tests have consistently higher power than EDF tests against almost all alternatives considered.