We read with interest the paper by Kemp and colleagues 1 which utilises cumulative sum (CUSUM) to analyse the learning curves associated with endobronchial ultra-sound-guided transbronchial needle aspiration (EBUS-TBNA). The retrospective study from five centres demonstrated that variable learning periods are required to attain proficiency in the procedure, and a pooled sensitivity of 67.4% was...

BACKGROUND Embryo transfer, a crucial step for achieving pregnancy after in vitro fertilization, is an operator-dependent technique but the number of procedures required for a trainee to reach proficiency is unknown. We set out to evaluate the learning curve (LC) of embryo transfer using a specifically designed statistical tool. METHODS The first embryo transfers performed by five trainees we...

Mukherjee and Chakraborti 1 proposed a single distribution-free (nonparametric) Shewhart-type chart based on the Lepage 2 statistic for simultaneously monitoring both the location and the scale parameters of a continuous distribution when both of these parameters are unknown. In the present work, we consider a single distribution-free CUSUM chart, based on the Lepage 2 statistic, referred to as...

BACKGROUND The lack of robust systems for monitoring quality in healthcare has been highlighted. Statistical process control (SPC) methods, utilizing the increasingly available routinely collected electronic patient records, could be used in creating surveillance systems that could lead to rapid detection of periods of deteriorating standards. We aimed to develop and test a CUmulative SUM (CUSU...

Comment Cusum plotting is clinically useful when a fever is swinging wildly and the overall trend is hidden, when other antimicrobial agents are given that are therapeutically unnecessary, and in patients in whom temperature remains raised but generally static. It indicates worsening of the fever despite antimicrobial treatment and thus discloses ineffective treatment. In this study the overall...

BACKGROUND Current methods available for assessing the learning curve, such as a predefined number of procedures or direct observation by a tutor, are unsatisfactory. A new tool, the cumulative summation test for learning curve (LC-CUSUM), has been developed that allows quantitative and individual assessment of the learning curve. METHODS Some 532 endoscopic retrograde cholangiopancreatograph...

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A distribution-free tabular CUSUM chart is designed to detect shifts in the mean of an autocorrelated process. The chart’s average run length (ARL) is approximated by generalizing Siegmund’s ARL approximation for the conventional tabular CUSUM chart based on independent and identically distributed normal observations. Control limits for the new chart are computed from the generalized ARL approx...