QUESTION TYPE: Weaken
CONCLUSION: The scent of peppermint must worsen insomnia.
REASONING: Two groups: one who inhaled bitter orange, one who inhaled peppermint. The peppermint inhalers had more trouble falling asleep. Bitter orange isn’t known to improve sleep.
ANALYSIS: These are patients with insomnia at a sleep clinic. They’re expected to sleep abnormally. My immediate thought on reading this was: what if there was a difference between the groups? I’d want to know that the groups were equal before concluding peppermint had any effect.
- This doesn’t affect anything. “Relaxing” doesn’t necessarily mean peppermint puts you to sleep. And insomnia patients could respond differently than patients without insomnia.
- CORRECT. This dramatically weakens the argument. Since the peppermint group had stronger insomnia, we’d expect them to have more trouble sleeping, no matter what they inhaled.
- This doesn’t do much. Most people in studies know they’re in studies!
If this had said “patients knew they were being given peppermint, which is widely believed to keep people awake” then this would weaken the argument by raising the possibility of a placebo effect.
But since both groups took something, then they’re both equally likely to experience a placebo effect.
- This is sad for those people, but it isn’t relevant. The study only focussed on how easy it was to fall asleep.
- This strengthens the argument by showing that scents can have an impact on sleep, in other cases. (If scents generally couldn’t impact sleep then the peppermint claim is less plausible.)
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