A stochastic queueing network model with parameter-dependent service times and routing mechanism, and its related performance measures are considered. An estimate of performance measure gradient is proposed, and rather general sufficient conditions for the estimate to be unbiased are given. A gradient estimation algorithm is also presented, and its validity is briefly discussed. Key-Words: queu...

The new hospital for the insane is intended for a daily average number of from 050 to 700 males and 175 to 200 female patients, and will be so situated and constructed that, as is not improbable, it will be capable of considerable extension in several directions. The area of land taken up is extensive, 'lhis is important, because it is fairly certain that a modern well-managed hospital of this ...

BACKGROUND Guidelines on cardiovascular disease (CVD) risk reassessment intervals are unclear, potentially leading to detrimental practice variation: too frequent can result in overtreatment and greater strain on the healthcare system; too infrequent could result in the neglect of high risk patients who require medication. This study aimed to understand the different factors that general practi...

BACKGROUND Many risk factors for fractures have been documented, including low bone-mineral density (BMD) and a history of fractures. However, little is known about the short-term absolute risk (AR) of fractures and the timing of clinical fractures. Therefore, we assessed the risk and timing of incident clinical fractures, expressed as 5-year AR, in postmenopausal women. METHODS In total, 10 ...

BACKGROUND Debate exists regarding to whether thiopurine therapy is as effective in ulcerative colitis (UC) as it is in Crohn's disease. AIM To review systematically the efficacy of azathioprine (AZA) and mercaptopurine (MP) in UC, and to conduct a meta-analysis of randomized clinical trials evaluating the efficacy of AZA/MP for the induction or maintenance of UC clinical remission. METHODS...

BACKGROUND National estimates of 'heart age' by government health organisations in the US, UK and China show most people have an older heart age than current age. While most heart age calculators are promoted as a communication tool for lifestyle change, they may also be used to justify medication when clinical guidelines advocate their use alongside absolute risk assessment. However, only thos...

We thank Drs. Selinger, Leong and McLaughlin for their interest and insightful comments on our work. Their previous study on patients' understanding and preference on methods of conveying statistical information is truly a pioneering work on this topic in the area of inflammatory bowel disease. The study shows the preference of patients for relative risk reduction (RR) over optical illustration...

Multivariate regression with p responses as opposed to p multiple regressions is getting increasingly more attention, especially in the context of prediction. Multivariate flattening methods are investigated as a way to obtain improved predictions over ordinary least-squares. With respect to sum of squares of prediction error, or SPE risk, an unbiased estimate of the risk is derived for two rec...

Hierarchical models are powerful statistical tools widely used in scientific and engineering applications. The homoscedastic (equal variance) case has been extensively studied, and it is well known that shrinkage estimates, the James-Stein estimate in particular, offer nice theoretical (e.g., risk) properties. The heteroscedastic (the unequal variance) case, on the other hand, has received less...

For independently distributed observables: Xi ∼ N(θi, σ2), i = 1, . . . , p, we consider estimating the vector θ = (θ1, . . . , θp) with loss ‖d− θ‖2 under the constraint ∑p i=1 (θi−τi) σ2 ≤ m2, with known τ1, . . . , τp, σ2,m. In comparing the risk performance of Bayesian estimators δα associated with uniform priors on spheres of radius α centered at (τ1, . . . , τp) with that of the maximum l...