1. An example from a carotid surgery trial showing how an intention to treat analysis is less biased than an on-treatment analysis.
An example from a carotid surgery trial showing how an intention to treat analysis is less biased than an on-treatment analysis. An on-treatment analysis compares group 2 with groups 3 and 4. The omission of group 1 will cause fewer strokes to be counted in the surgery arm, and therefore this analysis will be biased in favour of surgery. An intention to treat analysis compares groups 1 and 2 with groups 3 and 4, thus including all strokes.
S C Lewis, and C P Warlow J Neurol Neurosurg Psychiatry 2004;75:
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