Question

Be Sure to Get Your Beauty Sleep! New research1 supports the idea that people who get a good night's sleep look more attractive. In the study, 23 subjects ages 18 to 31 were photographed twice, once after a good night's sleep and once after being kept awake for 31 hours. Hair, make- up, clothing, and lighting were the same for both photographs. Observers then rated the photographs for attractiveness, and the average rating under the two conditions was compared. The researchers report in the British Medical Journal that "Our findings show that sleep-deprived people appear less attractive compared with when they are well rested." Stein, R., "Beauty sleep no myth, study finds", Washington Post, washingtonpost.com, accessed December 15,2010. (a) What is the explanatory variable? What is the response variable? (b) Is this an experiment or an observational study? If it is an experiment, is it a randomized comparative design or a matched pairs design? Observational study Matched pairs experiment Randomized comparative experiment

Answer 1

(a)

Here we are observing whether a good night's sleep affect attractiveness.

Thus, our explanatory variable is 'whether a person takes a good night's sleep' or 'amount of sleep'.

and our response variable is 'attractiveness' or 'level of attractiveness'.

(b)

Here each individual is photographed twice on both 'sleep deprivation'and 'good night's sleep'. That is each individual's attractiveness is measured on both the levels of the explanatory variable. Moreover, we are not observing some data but manipulating the response variable to measure the value of the explanatory variable.

Thus, this is a matched pairs experiment.

(c)

Here, an association was found between sleep deprivation and lack of attractiveness under an experimental study, thus we can conclude that sleep deprivation causes people to look less attractive.

But the study is not a randomized experiment.

Thus, the correct option is : Yes, we can, because an association was found and that is enough.

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Answer 2

explanatory variable - amount of rest response variable - attractiveness rating matched pairs experiment yes, we can, because an association was found and the result comes from a randomized experiment