Explaining the unbiased creation of treatment comparison groups and blinded outcome assessment

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• Format Texts
• Language/s English
• Target Audience Schools, Further education
• EBM Stage 0 - Why EBM?, 3 - Appraising evidence
• Duration >15 mins
• Difficulty Intermediate

Key Concepts addressed

• 2-1a Comparison groups should be similar
• 2-1d People should not know which treatment they get

Details

A class of 11-year-old children in Norway were given a supply of coloured sweets, and asked to design an experiment to find out whether red sweets helped children to think more quickly. The children pointed out that an experiment comparing the effects of red and non-red sweets would need to hide the colour of sweets from the participants: knowledge of the sweet colour might otherwise affect judgments about thinking speed. They understood the need to try to reduce the biases of the observers.

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