ExIStA Seminar October 2014

This joint ExIStA and RSS South West Local Group seminar was held on Friday 24th October 2014 between 2 and 3pm in Streatham Court Lecture Theatre D at the University of Exeter (No. 31 on the campus map).

Our invited speaker was Professor Stephen Senn, Head of the Competence Centre for Methodology and Statistics at CRP-Sante in Luxemboug. Stephen has extensive experience in both academia and industry and is recognized worldwide for his studies in statistical methodology applied to drug development.

Stephen gave a seminar on:

Mastering variation: Variance components and personalised medicine

It ought to be clear to any statistician that there are at least four potential sources of variation in clinical trials: the main effect of treatment, the main effects of patients, treatment-by-patient interaction and within-patient variation. It should also be obvious that identification of interactive effects requires replication at the level at which interaction is claimed. Hence treatment-by-patient interaction is only fully identifiable in multi-period cross-over trials, or, which amounts to the same thing, series of n-of-1 trials.

The medical literature, however, pays scant attention to these realities and it is plausible that much of the belief that the personal component in response is important is based on a misunderstanding that apparent observed difference in outcome must reflect differences in the effectiveness of treatment. Ironically, there is a fifth important source of variation that is nearly always overlooked: difference in medical practice.

It will be argued here that the key to improving the treatment of patients is to master variation and that this involves the following elements.

  1. Better communication of the problems by statisticians to their colleagues (some graphical approaches will be suggested).
  2. Application of decision analysis to determine when personalisation is worth pursuing.
  3. Appropriate design for teasing out components of variation.
  4. Application of random effect methodology for improving estimates.
  5. Translating from additive to relevant scales.
  6. Application of Deming´s ideas to understanding the system.
  7. Realistic monitoring and feedback.

Some suggestions for addressing these issues are given.

A copy of Stephen's slides are available here: StephenSenn.pdf and a video of the talk here.

If you have any questions about the event, please contact us at events@exista.org.

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