A neuroscientist suspects that low levels of the brain neurotransmitter serotonin may be causally related to aggressive behavior. As a fi rst step in investigating this hunch, she decides to do a...

A neuroscientist suspects that low levels of the brain neurotransmitter serotonin may be causally related to aggressive behavior. As a fi rst step in investigating this hunch, she decides to do a correlative study involving nine rhesus monkeys. The monkeys are observed daily for 6 months, and the number of aggressive acts is recorded. Serotonin levels in the striatum (a brain region associated with aggressive behavior) are also measured once per day for each animal. The resulting data are shown in the following table. The number of aggressive acts for each animal is the average for the 6 months, given on a per-day basis. Serotonin levels are also average values over the 6-month period.

a. Draw a scatter plot of the data.

b. If the data are linearly related, derive the least-squares regression line for predicting the number of aggressive acts from serotonin level.

c. On the basis of these data, what is the number of aggressive acts per day you would predict if a rhesus monkey had a serotonin level of 0.46 micro/ gm?