Question 1
(24 marks)
A human-computer interaction (HCI) researcher was interested in examining
whether humans are better able to use a joystick or a mouse to point a computer cursor.
She therefore constructed an experiment in which participants used either a joystick
(joystick condition) or a mouse (mouse condition) to point a cursor to a target displayed on
a computer monitor. She measured the time (seconds) that it took to place the cursor over
the target (dependent variable referred to as time, where a higher time score indicates
poorer performance). To determine whether potential benefits of using the joystick or
mouse generalized to difficult HCI scenarios, the target was either stationary (static
condition) or moved slowly across the computer screen at a constant velocity (motion
condition). Participants were randomly and uniquely assigned to 1 of 4 conditions in the
interface (levels: joystick, mouse) × target type (levels: static, motion) experimental design.
Given the data collected by the researcher (see Table 1 below), what can she conclude
about how easily humans interact these HCI interfaces and how are these HCI interfaces
influenced by target type? Include a line graph of the means.
3
Table 1. Target localization times in the interface × target type conditions.
Subject Interface Target Time
1 Joystick Static 2.53
2 Joystick Static 2.24
3 Joystick Static 3.16
4 Joystick Static 1.50
5 Joystick Static 3.06
6 Joystick Static 2.76
7 Joystick Static 2.57
8 Joystick Static 4.03
9 Joystick Static 1.70
10 Joystick Static 0.70
11 Joystick Motion 2.00
12 Joystick Motion 2.54
13 Joystick Motion 2.23
14 Joystick Motion 0.10
15 Joystick Motion 0.75
16 Joystick Motion 1.30
17 Joystick Motion 2.11
18 Joystick Motion 2.60
19 Joystick Motion 1.05
20 Joystick Motion 2.05
21 Mouse Static 1.39
22 Mouse Static 0.67
23 Mouse Static 1.62
24 Mouse Static 1.69
25 Mouse Static 0.29
26 Mouse Static 2.29
27 Mouse Static 0.93
28 Mouse Static 1.32
29 Mouse Static 0.33
30 Mouse Static 1.67
31 Mouse Motion 1.35
32 Mouse Motion 1.29
33 Mouse Motion 1.31
34 Mouse Motion 2.48
35 Mouse Motion 1.83
36 Mouse Motion 1.03
37 Mouse Motion 2.18
38 Mouse Motion 2.01
39 Mouse Motion 1.79
40 Mouse Motion 1.87
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Question 2
(11 marks)
A marketing team wants to determine which of two prospective product lines
consumers might prefer. They randomly select subjects to participate in a quantitative
focus group in which half of the participants were given product A, while the other half of
participants were given product B. Participants completed a questionnaire that probed
their affinity for the product they inspected during the focus group. Questionnaires items
were collapsed into a continuous-valued composite index of product affinity. In a
preliminary analysis, the marketing team ensured that the assumption of homogeneity of
variance was met:
???? =
????????
2
?????????
2 =
5.59
4.33 = 1.29, ????.???? = 4.04 .
Given the product affinity data they collected (see Table 2 below), which product are
consumers more likely to prefer? Show all relevant descriptive statistics.
Table 2. Product affinity scores for Product A and product B.
Subject Product Scores
1 A 3.27
2 A 2.52
3 A 4.83
4 A 0.68
5 A 4.59
6 A 3.84
7 A 3.35
8 A 7.00
9 A 1.19
10 A –1.32
11 B 2.69
12 B 4.04
13 B 3.26
14 B –2.08
15 B –0.44
16 B 0.93
17 B 2.97
18 B 4.17
19 B 0.30
20 B 2.80
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Question 3
(18 marks)
Sociologists investigated whether there is an association between salary and life
enjoyment. They administered questionnaires to randomly selected participants who
reported their salary in thousands of dollars (salary) and a battery of questionnaire items
that probe life enjoyment. The life enjoyment items were collapsed into a continuousvalued composite index of life enjoyment (LE). Given their data (see Table 3 below), is
there an association between salary and life enjoyment? If so, how does a change in salary
quantitatively relate to a change in life enjoyment? Include a scatterplot of the data and the
line of best fit.
Table 3. Salary in thousands of dollars (salary) and life enjoyment composite index (LE).
Subject salary LE
1 29 24
2 25 13
3 37 30
4 16 21
5 35 13
6 32 36
7 29 18
8 48 32
9 18 5
10 6 16
11 28 14
12 35 16
13 31 14
14 5 16
15 13 12
16 20 5
17 30 25
18 36 26
19 17 13
20 29 20
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Question 4
(10 marks)
Cognitive psychologists are examining the effect of visuospatial cueing on
perceptual processing speed. They designed an experiment in which a square randomly
appeared on either the left or right side of a computer monitor and participants were
required to push a button as soon as they detected the square. Each participant repeated
this action hundreds of times. On half of the trials, a quick flash of light preceded the
appearance of the square and it always appeared on the same side of the computer monitor
as the square (Cued condition). On the other half of the trials, no such flash occurred
(Control condition). The researchers measured the average time it took participants to
detect the square on trials in both the Cued and Control conditions (see Table 4 below).
What can the researchers conclude about the effect of visuospatial cueing on perceptual
processing speed? Show all relevant descriptive statistics.
Table 4. Mean subject reaction times (milliseconds) in the Cued and Control conditions.
Condition
Subject Cued Control
1 204 218
2 200 225
3 212 221
4 191 195
5 210 203
6 207 210
7 204 220
8 223 226
9 193 207
10 181 219
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Question 5
(7 marks)
A pharmaceutical company is interested in examining the efficacy of a new
experimental drug to reduce allergic reactions and therefore recruited subjects to
participate in a randomized clinical trial. The researchers exposed participants to a benign
allergen to elicit allergic reactions. Half of the participants were assigned to an
experimental drug treatment condition in which they were administered the new
experimental drug (Drug condition), while the remaining half of participants were placed
in a placebo condition in which they received a sham pharmacological treatment (Placebo
condition). They measured a continuous-valued, composite index of allergic reaction
symptomology to examine whether those who received the experimental drug treatment
showed a reduction in allergic reaction symptomology (see Table 5 below). Upon
preliminary analysis, the researchers discovered that the assumption of homogeneity of
variance was violated:
???? =
????????
2
?????????
2 =
6.79
1.67 = 4.07, ????.???? = 4.04 .
Furthermore, they realized that the dependent variable was not normally distributed, as
scores were heavily positively skewed. Given these observations, using a parametric
analysis of the mean difference between conditions is not appropriate. What can the
researchers conclude about the efficacy of the drug using a non-parametric analysis? Show
all relevant descriptive statistics.
Table 5. Composite allergic reaction symptomology scores in the Drug and Control
conditions.
Subject Condition Scores
1 Drug 1.05
2 Drug 0.70
3 Drug 2.10
4 Drug 0.20
5 Drug 1.91
6 Drug 1.38
7 Drug 1.09
8 Drug 4.41
9 Drug 0.29
10 Drug 0.02
11 Placebo 5.73
12 Placebo 8.21
13 Placebo 6.70
14 Placebo 1.00
15 Placebo 2.02
16 Placebo 3.33
17 Placebo 6.19
18 Placebo 8.47
19 Placebo 2.67
20 Placebo 5.92
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Short Answer (30 marks)
For these questions, you are given brief summaries of research scenarios and specific
hypotheses. You need to choose which statistical test is appropriate to analyze the
hypothesis given the context of the research scenario. Each scenario is worth 5 marks. 1
mark is for correctly identifying the appropriate statistical test. An additional 4 marks are
awarded for justifying your answer with respect to
- The type of data collected by researchers (i.e., continuous, ordinal, or nominal)
- Whether researchers are investigating an association/relationship between at least
two variables or are instead investigating differences between conditions using the
same variable - If applicable, the number of conditions and/or factors
- If applicable, the independence/dependence of observations between conditions
You may format your answers as either short paragraphs or bullet lists.
Question 1
(5 marks)
A vision scientist was examining whether human depth perception relies on
contextual visual information (i.e., depth cues). He constructed an experiment in which
participants viewed an object in virtual reality and had to estimate how far away the object
was. Participants repeated this many times and the researcher computed how accurately
participants were able to infer the depth of the object. Accuracy was operationalized as the
difference between participant estimates of object distance and the true distance of the
object. On half of the trials, the object appeared in a long hallway with realistic décor, thus
providing contextual depth cues. On the other half of trials, the object appeared in a white
void of empty space. Participants experienced both trial types in randomized order and
their accuracy was compared between the hallway and void conditions. If depth is inferred
from visual cues, accuracy should be lower in the void condition than in the hallway
condition. What analysis should the vision scientist perform to examine whether subjects
we less able to infer depth when deprived of depth cues?
Question 2
(5 marks)
A zoologist was interested in investigating whether non-human primates (NHPs)
experience attentional “pop-out”; that is, when you are visually searching for something in
a cluttered environment, the object you are looking for can either be difficult to find or is
immediately obvious—it “pops out”. Therefore, they constructed an experiment in which
NHPs were trained to locate an object amongst clutter and he measured how long it took
the NHPs to locate the object. In the baseline condition, the object was presented alone.
The researcher also included 2 additional conditions in which the object was presented
amongst low-levels of clutter or high-levels of clutter. The NHPs completed each condition
in randomized order. If NHPs experience “pop-out”, locating the object should take equally
as long in in the baseline condition as it does in both cluttered conditions. Which analysis
should the zoologist perform?
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Question 3
(5 marks)
A sociologist wanted to investigate how well a person’s salary can be predicted by
the combination of their intelligence quotient (IQ) and the number of years they have been
formally educated. She therefore published a survey in which participants self-reported
their salary in dollars, completed an IQ battery, and self-reported the number of years they
have spent in post-secondary education. The IQ questionnaire was collapsed into a
continuous-valued composite IQ index. What analysis should the researcher perform to
assess the combined influence of IQ and educational attainment on salary?
Question 4
(5 marks)
An educational psychologist was curious whether students who consistently sit in
the front row of lectures achieved higher grades than students who consistently sit in the
back row. He published an online survey available to university students in which
participants self-reported which row they sat in during lectures throughout the semester
and the their final grade point average at the end of the semester. He was interested in
comparing the grade point averages of two groups of students: those who sat in front of the
class and those who sat in the back. What analysis should he perform?
Question 5
(5 marks)
A self-proclaimed health and wellness company contracted statisticians to examine
the efficacy of their newly developed dieting program. They provided the statisticians with
data from a publicized weight loss competition that they hosted to advertise the release of
their new product. For the competition, participants completed the dieting program and
were ranked in order of the amount of weight they lost pre- and post-completion of the
program. What statistical analysis could the statisticians perform to assess the efficacy of
the dieting program?
Question 6
(5 marks)
A personality psychologist was interested in examining whether the prevalence of
narcissism differed between people based on the type of pet they own: cats, dogs, or exotic
pets. She administered a questionnaire that probed narcissistic personality traits to
randomly selected participants. She collapsed the questionnaire items into a continuousvalued composite index of narcissism prevalence. She included biological sex as a factor in
her analysis to examine whether biological sex interacts with pet type to influence the
prevalence of narcissism. This gave her a 2×3 experimental design with sex (men, women)
and pet type (cat, dog, exotic) as factors.
Sample Solution
