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Educational tests often have a cluster of items linked by a common stimulus (testlet). In such a design, the dependencies caused between items are called testlet effects. In particular, the directional testlet effect (DTE) refers to a recursive influence whereby responses to earlier items can positively or negatively affect the scores on later items. This study aims to introduce an innovative measurement model to describe DTEs among multiple polytomouslyscored open‐ended items. Through simulations, we found that (1) item and DTE parameters can be accurately recovered in Latent GOLD®, (2) ignoring positive (or negative) DTEs by fitting a standard item response theory model can result in the overestimation (or underestimation) of test reliability, (3) collapsing multiple items of a testlet into a super item is still effective in eliminating DTEs, (4) the popular multidimensional strategy of adding nuisance factors to describe item dependencies fails to account for DTE adequately, and (5) fitting the proposed model for DTE to testlet data involving nuisance factors will observe positive DTEs but will not have a better fit. Moreover, using the proposed model, we demonstrated the coexistence of positive and negative DTEs in a real history exam. [ABSTRACT FROM AUTHOR]

Multiple‐choice (MC) items are widely used in educational tests. Distractor analysis, an important procedure for checking the utility of response options within an MC item, can be readily implemented in the framework of item response theory (IRT). Although random guessing is a popular behavior of test‐takers when answering MC items, none of the existing IRT models for distractor analysis have considered the influence of random guessing in this process. In this article, we propose a new IRT model to distinguish the influence of random guessing from response option functioning. A brief simulation study was conducted to examine the parameter recovery of the proposed model. To demonstrate its effectiveness, the new model was applied to the mathematics tests of the Hong Kong Diploma of Secondary Education Examination (HKDSE) from 2015 to 2019. The results of empirical analyses suggest that the complexity of item contents is a key factor in inducing students' random guessing. The implications and applications of the new model to other testing situations are also discussed. [ABSTRACT FROM AUTHOR]

The green space of Hong Kong was studied using a normalized difference vegetation index (NDVI) derived from SPOT images. Spatial patterns of the magnitude and variability of 'greenness' were analyzed based on the mean and entropy of NDVI at the tertiary planning unit (TPU) level. Continuous loss of green space due to urban encroachment and hill fires was identified in many parts of the territory between 1987 and 1995. However, establishment of green belts and improved landscaping, as found in many new development projects, such as the Tsang Kwan O new town, resulted in the continuous gain in green space or percentage of woodland in a few locations. [ABSTRACT FROM AUTHOR]

Background. Most documented "superspreading events" of severe acute respiratory syndrome (SARS) occurred in hospitals, but the underlying causes remain unclear. We systematically analyzed the risk factors for nosocomial outbreaks of SARS among hospital wards in Guangzhou and Hong Kong, China. Methods. A case-control study was conducted. Case wards were hospital wards in which superspreading events of SARS occurred, and control wards were wards in which patients with SARS were admitted, but no subsequent nosocomial outbreaks occurred. Information on environmental and administrative factors was obtained through visits to the wards and interviews with ward managers or nursing officers. Relevant information about host factors was abstracted from the medical records. Logistic regression analyses were used to identify the major risk factors for superspreading events. Results. Eighty-six wards in 21 hospitals in Guangzhou and 38 wards in 5 hospitals in Hong Kong were included in the study. Six risk factors were significant in the final multiple-logistic regression model: minimum distance between beds of ⩽1 m (odds ratio [OR], 6.94; 95% confidence interval [CI], 1.68-28.75), availability of washing or changing facilities for staff (OR, 0.12; 95% CI, 0.02-0.97), whether resuscitation was ever performed in the ward (OR, 3.81; 95% CI, 1.04-13.87), whether staff members worked while experiencing symptoms (OR, 10.55; 95% CI, 2.28-48.87), whether any host patients (index patient or the first patient with SARS admitted to a ward) required oxygen therapy (OR, 4.30; 95% CI, 1.00-18.43), and whether any host patients required bi-level positive airway pressure ventilation (OR, 11.82; 95% CI, 1.97-70.80). Conclusions. Our results revealed that factors that were associated with the ward environment and administration were important in nosocomial outbreaks of SARS. The lessons learned from this study remain very important and highly relevant to the daily operation of hospital wards if we are to prevent nosocomial outbreaks of other respiratory infections in the future. [ABSTRACT FROM AUTHOR]