An article entitled "Too Few Z's May Result in Too Many Pounds" tells about two studies published in 2004 in the Annals of Internal Medicine, which show that "loss of sleep boosts levels of a hormone that tells us we're hungry, while dropping levels of a hormone that signals the body that we're full. Researchers have noticed that increased obesity among Americans has coincided with less time spent asleep. In 1960, U.S. adults slept an average of more than 8 hours a night; by 2002, the average had fallen to less than 7 hours. At the same time, in 1960, one in four adults was considered overweight and one in nine was considered obese; now two in three are overweight and nearly one in three is obese."22
a. Apparently there is a relationship between amount of sleep and levels of a hormone that tells us we're hungry. Is this relationship positive or negative?
b. There is also an apparent relationship between amount of sleep and levels of a hormone that tells us we're full. Is this relationship positive or negative?
c. The last two sentences of the previous quote have to do with the relationship between sleep and weight. Tell whether the variable for sleep is being treated as quantitative or categorical.
d. Tell whether the variable for weight is being treated as quantitative or categorical.