New research supports the idea that people who get a good night's sleep look more at 31 were photographed twice, once after a good night's sleep and once after being kept
and lighting were the same for both photographs. Observers then rated the photograp
under the two conditions was compared. The researchers report in the British Medical
deprived people appear less attractive compared with when they are well rested."
1Stein, R., "Beauty sleep no myth, study finds", Washington Post, washingtonpost. com, ac
(a) What is the explanatory variable?