TABLE 17-12
The marketing manager for a nationally franchised lawn service company would like to
study the characteristics that differentiate home owners who do and do not have a lawn
service. A random sample of 30 home owners located in a suburban area near a large
city was selected; 15 did not have a lawn service (code 0) and 15 had a lawn service
(code 1). Additional information available concerning these 30 home owners includes
family income (Income, in thousands of dollars), lawn size (Lawn Size, in thousands of
square feet), attitude toward outdoor recreational activities (Attitude 0 = unfavorable, 1
= favorable), number of teenagers in the household (Teenager), and age of the head of
the household (Age).
The Minitab output is given below:
Referring to Table 17-12, what should be the decision (‘reject’ or ‘do not reject’) on the
null hypothesis when testing whether LawnSize makes a significant contribution to the
model in the presence of the other independent variables at a 0.05 level of significance?
TABLE 10-6
To investigate the efficacy of a diet, a random sample of 16 male patients is selected
from a population of adult males using the diet. The weight of each individual in the
sample is taken at the start of the diet and at a medical follow-up 4 weeks later.
Assuming that the population of differences in weight before versus after the diet
follow a normal distribution, the t-test for related samples can be used to determine if
there was a significant decrease in the mean weight during this period. Suppose the
mean decrease in weights over all 16 subjects in the study is 3.0 pounds with the
standard deviation of differences computed as 6.0 pounds.
Referring to Table 10-6, the t test should be ________-tail.