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Bias may be defined as any systematic error in a study that results in an incorrect result; confounding occurs when the groups being compared differ with respect to another factor or ‘confounder’ which is associated with the outcome (or disease) under study. Both bias and confounding can be thought of as alternative explanations for the observed effect.
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Evans, J. Randomised controlled trials. Eye 9, 684–685 (1995). https://doi.org/10.1038/eye.1995.179
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DOI: https://doi.org/10.1038/eye.1995.179