The distribution of the range of a sample, even in the case of a normal distribution, is not symmetric. Shewhart’s control chart for range and other approximations for range from skewed distributions and long-tailed (leptokurtic) symmetrical distributions assume the distribution of range as symmetric and provide ±3 sigma control limits. We provide accurate approximations for the R-chart control...

background: taking visual acuity is an important part of an eye routine examination. this study was conducted to compare visual acuity measured using an iranian digital tumbling e chart with visual acuity measured using an italian digital tumbling e chart as a familiar foreign chart. materials and methods: this study was carried out on 200 participants (400 eyes; healthy n=40, glaucoma n=40, re...

multivariate control charts such as hotelling`s t^ 2 and x^ 2 are commonly used for monitoring several related quality characteristics. these control charts use correlation structure that exists between quality characteristics in an attempt to improve monitoring. the purpose of this article is to discuss some issues related to the g chart proposed by levinson et al. [9] for detecting shifts in ...

OBJECTIVES To evaluate the feasibility, applicability and the value of customised symphysio fundal height (SFH) charts developed for women of Indian origin in the United Kingdom (UK: CSFH - In chart) and women of African origin in the UK (CSFH - Af chart) in detecting fetal growth restriction and predicting low birth weight (LBW) of the neonate in a Lankan population, and to compare these resul...

We propose a new multivariate CUSUM control chart, which is based on selfadaption of its reference value according to the information of current process readings, to quickly detect the multivariate process mean shifts. By specifying the minimum magnitude of the process mean shift in terms of its non-centrality parameter, our proposed control chart can achieve an overall performance for detectin...

background: general practitioners are the first who visit burn patients and they first calculate burn size and required fluid for the patient. error in calculation can be disastrous. the purpose of this study is to compare four methods of estimating burn size to teach students. methods: this is a descriptive-analytic study on 37 medical students. four methods of estimating burn percentage was t...

This paper proposes a new adaptive chart based on the Shiryaev-Roberts procedure, by updating the reference value in an adaptive way to achieve the aim of overall good performance over a range of future expected but unknown mean shifts. A two-dimensional Markov chain model is developed to analyze the run length performance. The design guidelines are given. The comparisons of run length performa...