Refer to the World Development (Feb. 1998) study of street vendors in the city of Puebla, Mexico, Exercise 10.7 (p. 573). Recall that the vendors' mean annual earnings Eb) was modeled as a first-order function of age x1 and hours worked x2. Refer to the STATISTIX printout on p. 573 and answer the following.
a. Interpret the value of R2.
b. Interpret the value of 
Explain the relationship between R2 and 
c. Conduct a test of the global utility of the model at α = .01. Interpret the result
Exercise 10.7
Detailed interviews were conducted with over 1,000 street vendors in the city of Puebla, Mexico, in order to study the factors influencing vendors' incomes (World Development, Feb. 1998). Vendors were defined as individuals working in the street, and included vendors with carts and stands on wheels and excluded beggars, drug dealers, and prostitutes. The researchers collected data on gender, age, hours worked per day, annual earnings, and education level. A subset of these data appear in the table on page 574
a. Write a first-order model for mean annual earnings, Eb), as a function of age (x1) and hours worked (x2).
b. The model was fit to the data using STATISTIX. Find the least squares prediction equation on the printout shown below.
c. Interpret the estimated ß coefficients in your model.
d. Is age x1 a statistically useful predictor of annual earnings? Test using a = .01
e. Construct a 99% confidence interval for ß2. Interpret the interval in the words of the problem.
