Article first published online: 19 JUN 2012
Copyright © 2012 John Wiley & Sons, Ltd.
Statistics in Medicine
Volume 31, Issue 28, pages 3649–3655, 10 December 2012
How to Cite
Heller, G. Z. and Dunlop, L. C. (2012), A modelling approach for blood units transfused after stem cell transplantation. Statist. Med., 31: 3649–3655. doi: 10.1002/sim.5415
- Issue published online: 23 NOV 2012
- Article first published online: 19 JUN 2012
- Manuscript Accepted: 24 MAR 2012
- Manuscript Received: 10 OCT 2011
- digit preference;
- loglinear regression
Patients undergoing stem cell transplantation may require transfusion of units (bags) of packed red blood cells (PRBCs). Modelling of PRBC usage is important not only for prediction of transfusion requirements in future patients but also for its use as an inverse surrogate for engraftment, that is transplantation success. Inspection of PRBC unit usage reveals a strong preference for even numbers, which is caused by behavioural preference on the part of prescribing physicians. Digit preference is a phenomenon observed more commonly with self-reported data: typically survey respondents round recalled quantities such as the age at which a life event occurred to multiples of 5 or 10. In all cases, we can conceive of a latent variable, which has a smooth distribution, which is transformed via stochastic rules to a discrete variable with probability spikes at preferred digits. We propose a modelling framework based on a latent variable specification and stochastic transformation to the spiked distribution. Loglinear models for the mean of the process are implemented. Specification of the stochastic rules is important to success in accurate modelling of the process. Copyright © 2012 John Wiley & Sons, Ltd.