Graphical sensitivity analysis with different methods of imputation for a trial with probable non-ignorable missing data


Weatherall, Mark, Pickering, R.M. and Harris, S. (2005) Graphical sensitivity analysis with different methods of imputation for a trial with probable non-ignorable missing data At Wellington Statistics Group (WSG). 13 Apr 2005.

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Description/Abstract

Graphical sensitivity analyses have recently been recommended for clinical trials with non-ignorable missing binary outcome. We demonstrate an adaptation of this methodology for a continuous outcome of a trial of three cognitive-behavioural therapies for mild depression in primary care, in which one arm had unexpectedly high levels of missing data. Fixed value and multiple imputation from a normal distribution (assuming either varying mean and fixed SD, or fixed mean and varying SD) were used to obtain contour plots of the contrast estimates with their P values superimposed; their confidence interval; and the root mean square error. Imputation was based on both the outcome value alone, or on change from baseline. The plots showed fixed value imputation to be more sensitive than imputing from a normal distribution, but the normally distributed imputations were subject to sampling noise. The contours of the sensitivity plots were close to linear in appearance with the slope approximately equal to the ratio of the proportions of subjects with missing data in each trial arm.

Item Type: Conference or Workshop Item (Other)
Venue - Dates: Wellington Statistics Group (WSG), 2005-04-13 - 2005-04-13
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Keywords: imputation, missing data, analysis, methods, trial
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ePrint ID: 62198
Date :
Date Event
2005Published
Date Deposited: 17 Apr 2009
Last Modified: 16 Apr 2017 17:29
Further Information:Google Scholar
URI: http://eprints.soton.ac.uk/id/eprint/62198

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