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


Weatherall, M. Pickering, R.M. and Harris, Scott (2009) Graphical sensitivity analysis with different methods of imputation for a trial with probable non-ignorable missing data. Australian and New Zealand Journal of Statistics, 51, (4), 397-413. (doi:10.1111/j.1467-842X.2009.00553.x).

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Description/Abstract

Graphical sensitivity analyses have recently been recommended for clinical trials with nonignorable
missing 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 imputations from a normal distribution (assuming either varying mean and fixed
standard deviation, or fixed mean and varying standard deviation) were used to obtain contour
plots of the contrast estimates with their P-values superimposed, their confidence intervals,
and the root mean square errors. Imputation was based either on 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: Article
ISSNs: 1369-1473 (print)
1467-842X (electronic)
Keywords: imputation, missing data, randomized controlled trial, sensitivity analysis
Subjects: R Medicine > R Medicine (General)
Divisions: University Structure - Pre August 2011 > School of Medicine > Community Clinical Sciences
ePrint ID: 147729
Date Deposited: 26 Apr 2010 12:45
Last Modified: 27 Mar 2014 19:08
URI: http://eprints.soton.ac.uk/id/eprint/147729

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