True or False: Selection bias occurs more frequently in systematic samples than in
simple random samples.
True or False: Suppose, in testing a hypothesis about a mean, the Z test statistic is
computed to be 2.04. The null hypothesis should be rejected if the chosen level of
significance is 0.01 and a two-tail test is used.
True or False: Cp > 1 indicates that if the process average can be centered, then more
than 99.73% of the observations will fall inside the specification limits.
TABLE 13-3
The director of cooperative education at a state college wants to examine the effect of
cooperative education job experience on marketability in the work place. She takes a
random sample of 4 students. For these 4, she finds out how many times each had a
cooperative education job and how many job offers they received upon graduation.
These data are presented in the table below.
True or False: Referring to Table 13-3, suppose the director of cooperative education
wants to construct both a 95% confidence interval estimate and a 95% prediction
interval for X = 2. The confidence interval estimate would be the wider of the two
intervals.
True or False: To test whether one proportion is higher than the other in two related
samples, you can use the Marascuilo procedure.
True or False: TABLE 17-10
Given below are results from the regression analysis where the dependent variable is
the number of weeks a worker is unemployed due to a layoff (Unemploy) and the
independent variables are the age of the worker (Age), the number of years of education
received (Edu), the number of years at the previous job (Job Yr), a dummy variable for
marital status (Married: 1 = married, 0 = otherwise), a dummy variable for head of
household (Head: 1 = yes, 0 = no) and a dummy variable for management position
(Manager: 1 = yes, 0 = no). We shall call this Model 1. The coefficient of partial
determination ( ) of each of the 6 predictors are, respectively,
0.2807, 0.0386, 0.0317, 0.0141, 0.0958, and 0.1201.
Model 2 is the regression analysis where the dependent variable is Unemploy and the
independent variables are Age and Manager. The results of the regression analysis are
given below:
Referring to Table 17-10, Model 1, the alternative hypothesis H1 : At least one of βj â
‰ 0 for j = 1, 2, 3, 4, 5, 6 implies that the number of weeks a worker is unemployed
due to a layoff is related to at least one of the explanatory variables.
True or False: TABLE 17-8
The superintendent of a school district wanted to predict the percentage of students
passing a sixth-grade proficiency test. She obtained the data on percentage of students
passing the proficiency test (% Passing), daily mean of the percentage of students
attending class (% Attendance), mean teacher salary in dollars (Salaries), and
instructional spending per pupil in dollars (Spending) of 47 schools in the state.
Following is the multiple regression output with Y = % Passing as the dependent
variable, X1 = % Attendance, X2 = Salaries and X3 = Spending:
Referring to Table 17-8, the alternative hypothesis H1 : At least one of βj ≠0 for j =
1, 2, 3 implies that the percentage of students passing the proficiency test is affected by
all of the explanatory variables.
TABLE 11-10
An agronomist wants to compare the crop yield of 3 varieties of chickpea seeds. She
plants all 3 varieties of the seeds on each of 5 different patches of fields. She then
measures the crop yield in bushels per acre. Treating this as a randomized block design,
the results are presented in the table that follows.
True or False: Referring to Table 11-10, based on the Tukey multiple comparison
procedure with an overall level of significance of 0.01, the agronomist would decide
that there is a significant difference between the crop yield of Smith and Walsh seeds.
TABLE 9-3
An appliance manufacturer claims to have developed a compact microwave oven that
consumes a mean of no more than 250 W. From previous studies, it is believed that
power consumption for microwave ovens is normally distributed with a population
standard deviation of 15 W. A consumer group has decided to try to discover if the
claim appears true. They take a sample of 20 microwave ovens and find that they
consume a mean of 257.3 W.
True or False: Referring to Table 9-3, for this test to be valid, it is necessary that the
power consumption for microwave ovens has a normal distribution.
TABLE 11-4
An agronomist wants to compare the crop yield of 3 varieties of chickpea seeds. She
plants 15 fields, 5 with each variety. She then measures the crop yield in bushels per
acre. Treating this as a completely randomized design, the results are presented in the
table that follows.
Referring to Table 11-4, the within-group variation or SSW is ________.
The residual represents the discrepancy between the observed dependent variable and
its ________ value.
You were told that the amount of time lapsed between consecutive trades on the New
York Stock Exchange followed a normal distribution with a mean of 15 seconds. You
were also told that the probability that the time lapsed between two consecutive trades
to fall between 16 to 17 seconds was 13%. The probability that the time lapsed between
two consecutive trades would fall below 13 seconds was 7%. The middle 86% of the
time lapsed will fall between which two numbers?
TABLE 2-12
The table below contains the opinions of a sample of 200 people broken down by
gender about the latest congressional plan to eliminate anti-trust exemptions for
professional baseball.
Referring to Table 2-12, ________ percent of the 200 were females who were either
neutral or against the plan.
TABLE 17-8
The superintendent of a school district wanted to predict the percentage of students
passing a sixth-grade proficiency test. She obtained the data on percentage of students
passing the proficiency test (% Passing), daily mean of the percentage of students
attending class (% Attendance), mean teacher salary in dollars (Salaries), and
instructional spending per pupil in dollars (Spending) of 47 schools in the state.
Following is the multiple regression output with Y = % Passing as the dependent
variable, X1 = % Attendance, X2 = Salaries and X3 = Spending:
Referring to Table 17-8, what is the value of the test statistic to determine whether there
is a significant relationship between the percentage of students passing the proficiency
test and the entire set of explanatory variables?
TABLE 3-1
Health care issues are receiving much attention in both academic and political arenas. A
sociologist recently conducted a survey of citizens over 60 years of age whose net
worth is too high to qualify for Medicaid. The ages of 25 senior citizens were as
follows:
Referring to Table 3-1, calculate the standard deviation of the ages of the senior citizens
correct to the nearest hundredth of a year.
TABLE 13-4
The managers of a brokerage firm are interested in finding out if the number of new
clients a broker brings into the firm affects the sales generated by the broker. They
sample 12 brokers and determine the number of new clients they have enrolled in the
last year and their sales amounts in thousands of dollars. These data are presented in the
table that follows.
Referring to Table 13-4, the coefficient of determination is ________.
TABLE 2-14
The table below contains the number of people who own a portable Blu-ray player in a
sample of 600 broken down by gender.
Referring to Table 2-14, of those who did not own a portable Blu-ray player in the
sample, ________ percent were males.
TABLE 14-10
You worked as an intern at We Always Win Car Insurance Company
last summer. You notice that individual car insurance premiums
depend very much on the age of the individual and the number of
tra&c tickets received by the individual. You performed a regression
analysis in EXCEL and obtained the following partial information:
Referring to Table 14-10, the proportion of the total variability in
insurance premiums that can be explained by AGE and TICKETS is
________.
TABLE 13-5
The managing partner of an advertising agency believes that his company’s sales are
related to the industry sales. He uses Microsoft Excel to analyze the last 4 years of
quarterly data (i.e., n = 16) with the following results:
Referring to Table 13-5, the value of the quantity that the least squares regression line
minimizes is ________.