The following model is a simplified version of the multiple regression model used by Biddle and Hamermesh (1990) to study the tradeoff between time spent sleeping and working and to look at other factors affecting sleep:

sleep=B_0+B_1 totwork+B_2 educ+B_3 age+u
Where sleep and totwork(total work) are measured in minutes per week and educ and age are measured in years.
1: If adults trade off sleep for work what is the sign of B_1?
2: What signs do you think of B_2and B_3?
3: Suppose the estimated equation is;
(sleep) ̂=3638.25-0.148totwork-11.13educ+2.20age
n=706 and R^2= 0.113
3: If someone works five more hours per week, by how many minutes sleep is predicted to fall? Is this a large trade off?
4: Discuss the sign and magnitude of the estimated coefficient on educ
5:Would you say, totwork, educand age explain much of the variation in sleep? What other factor affect the time spent sleeping? Are these likely to be correlated withtotwork?