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Risk‐adjusted survival time monitoring with an updating exponentially weighted moving average (EWMA) control chart
Author(s) -
Steiner Stefan H.,
Jones Mark
Publication year - 2009
Publication title -
statistics in medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.996
H-Index - 183
eISSN - 1097-0258
pISSN - 0277-6715
DOI - 10.1002/sim.3788
Subject(s) - ewma chart , control chart , chart , computer science , statistics , moving average , set (abstract data type) , data mining , medicine , mathematics , process (computing) , operating system , programming language
Monitoring medical outcomes is desirable to help quickly detect performance changes. Previous applications have focused mostly on binary outcomes, such as 30‐day mortality after surgery. However, in many applications the survival time data are routinely collected. In this paper, we propose an updating exponentially weighted moving average (EWMA) control chart to monitor risk‐adjusted survival times. The updating EWMA (uEWMA) operates in a continuous time; hence, the scores for each patient always reflect the most up‐to‐date information. The uEWMA can be implemented based on a variety of survival‐time models and can be set up to provide an ongoing estimate of a clinically interpretable average patient score. The efficiency of the uEWMA is shown to compare favorably with the competing methods. Copyright © 2009 John Wiley & Sons, Ltd.