Selection models for repeated measurements with non-random dropout: an illustration of sensitivity
✍ Scribed by Michael G. Kenward
- Publisher
- John Wiley and Sons
- Year
- 1998
- Tongue
- English
- Weight
- 83 KB
- Volume
- 17
- Category
- Article
- ISSN
- 0277-6715
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✦ Synopsis
The outcome-based selection model of Diggle and Kenward for repeated measurements with non-random dropout is applied to a very simple example concerning the occurrence of mastitis in dairy cows, in which the occurrence of mastitis can be modelled as a dropout process. It is shown through sensitivity analysis how the conclusions concerning the dropout mechanism depend crucially on untestable distributional assumptions. This example is exceptional in that from a simple plot of the data two outlying observations can be identified that are the source of the apparent evidence for non-random dropout and also provide an explanation of the behaviour of the sensitivity analysis. It is concluded that a plausible model for the data does not require the assumption of non-random dropout.