A dose comparison for middle-of-the-night insomnia

Topic: Studies, data, and evidence · more questions on this topic
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Twenty-four patients with middle-of-the-night insomnia are randomly allocated to placebo, a low dose of triazolam, or a high dose. After two weeks, both active doses show a longer total sleep time than placebo.

  1. What type of study is this?

  2. What values can total sleep time take, and what type of variable is it?

  3. What values can dosage take, and what type of variable is it?

  4. Which variable is the response, and why?

  1. A randomised designed experiment, a randomised controlled trial with a placebo arm.

  2. Total sleep time is a duration, any non-negative number of minutes, so it is quantitative and continuous, though recorded to the nearest minute.

  3. Dosage takes three values: placebo, low and high. It is categorical and ordinal, since the levels have a natural order. If the actual doses in milligrams were used, it could also be treated as quantitative.

  4. Total sleep time is the response, because it is the outcome the drug is meant to change, and the dose is what the investigators set.