Intermediate Statistical Investigations
by Nathan Tintle, Beth L. Chance
1st Edition
N
U
R
SE
D
O
C
S
JHGFDS
, Chapter 1
Intermediate Statistical Investigations Test Bank
Question types: FIB = Fill in the blank Calc = Calculation
Ma = Matching MS = Multiple select
MC = Multiple choice TF = True-false
CHAPTER 1 TERMINAL LEARNING OUTCOMES
TLO1-1: Apply the six-step investigative process in the context of a well-designed experiment.
TLO1-2: Partitioning variation in the response variable into variation explained by the model and
unexplained variation, and measuring and reporting the percentage of variation explained
N
TLO1-3: Assess the statistical significance of the difference between two groups on a quantitative
response variable using both simulation and theory-based approaches
TLO1-4: Compare more than two treatments on a quantitative response using both simulation
U
and theory-based approaches
TLO1-5: Apply Post-hoc analysis after significant F-test (pairwise differences, as well as
confidence and prediction intervals for single means)
R
TLO1-6: Understand statistical power and how it is impacted by sample size, variability within
groups, number of groups, and significance level
SE
Section 1.1: Sources of Variation in an Experiment
LO1.1-1: Apply the six-step investigative process.
LO1.1-2: Distinguish experiments and observational studies.
LO1.1-3: Review basic study design principles such as inclusion criteria and random assignment.
D
LO1.1-4: Define terminology specific to an experimental study (e.g., treatments).
LO1.1-5: Produce a Sources of Variation diagram for an experiment.
O
Questions 1 through 3: A study published in Psychological Science in 2007 examined a possi-
ble link between mindset and health. The following is an excerpt from the abstract of the
article: ―84 female room attendants working in seven different hotels were measured on
C
physiological health variables affected by exercise. Those in the informed condition were
told that the work they do (cleaning hotel rooms) is good exercise and satisfies the Sur-
geon General's recommendations for an active lifestyle. Examples of how their work was
S
exercise were provided. Subjects in the control group were not given this information. ‖
1. Identify the experimental units in this study.
A. The eighty-four room attendants
KJHGFEDW
, S
C
O
D
SE
R
U
N
, KJHGFDS
B. The seven different hotels
C. The physiological health variables
D. The two groups (informed and control)
Ans: A; LO: 1.1-4; Difficulty: Easy; Type: MC
2. The researchers chose to include room attendants from seven different hotels (as op-
posed to using stricter inclusion criteria that would limit the study to room attendants at
one particular hotel). Describe the consequences of this decision.
Using broader inclusion criteria may (increase/decrease) the amount of variation
in the observed health outcomes. However, this decision also (sup-
ports/limits) generalizability to a larger population of room attendants.
N
Ans: increase, supports; LO: 1.1-3; Difficulty: Medium; Type: FIB
U
3. Room attendants were randomly assigned to either the informed condition or the control
group. What is the most important reason for the random assignment?
A. Random assignment ensures that the study is double-blind.
R
B. Random assignment reduces the impact of outliers.
C. Random assignment creates two groups of room attendants that are as similar as
possible, which supports cause-and-effect conclusions.
D. Random assignment makes it possible to generalize the results to the population.
SE
Ans: C; LO: 1.1-3; Difficulty: Medium; Type: MC
Questions 4 through 6: An online retailer is using an experiment to decide whether to modify
their website. When visitors type in the web address or click a link to the site, they are
D
randomly re-directed to one of two versions of the website: the version that has been in
use for the last year (version A) or an updated version (version B). The retailer’s goal is to
maximize the amount of time (in minutes) visitors stay on the site.
O
4. Identify the experimental units and variables. Note: One of the answer choices will not be
used.
Experimental units: A. Version of the website (A and B)
C
Explanatory variable: B: Online retailers
Response variable: C: Visitors to the website
D: Time spent on the website (in minutes)
S
Ans: Experimental units: C, Explanatory variable: A, Response variable: D; LO: 1.1-4;
Difficulty: Easy; Type: Ma
5. Consider two possible models for analyzing time spent on this retailer’s website.
Single-mean model:
A. Predicted timespent onsite =12.33, SEof residuals =4.64
Separate-means model: