The document presents the results of two studies that compared different visualization techniques for displaying multi-scale documents: focus plus context (f+c), overview plus detail (o+d), and zooming plus panning (z+p). Study 1 found that tasks were completed faster and users were more satisfied with f+c displays compared to o+d and z+p displays for static documents. Study 2 found that for dynamic document tasks, f+c displays resulted in fewer errors than o+d displays. The studies provide evidence that f+c screens may enable individual monitoring and interaction tasks that typically require multiple users.

1. Keeping Things in Context: A
Comparative Evaluation
of Focus Plus Context Screens,
Overviews, and Zooming
Patrick Baudisch, Nathaniel Good, Victoria Bellotti, & Pamela Schraedley
Information Sciences and Technologies Lab/Computer Science Lab
Xerox Palo Alto Research Center
Presented By Debaleena Chattopadhyay
I590, Summer 2012

2. Revisiting Definitions
Multi-scale Documents Static
Visual documents that are
Documents that remain
too large and detailed to fit
unchanged unless the user
on user’s computer screen
modifies them.
at a time.
E.g. maps.
E.g. maps, design diagrams.
Dynamic
Information streams that
are changing irrespective
of user involvement.
E.g. games, air traffic
control.
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3. Revisiting Definitions (contd..)
f+c z+p
Focus + Context is a Zooming and
visualization technique for panning is a
very large and detailed technique to
documents. display required
information
They contain wall-size low- sequentially in
res displays as context terms of different
screens and an embedded views.
high-res display region
called focus.
o+d
Overview + Detail is a multi-window (usually two)
visualization technique.
They contain one window (overview) which always
displays the entire document, while another window
(detail) shows a certain close-up.
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4. Legends
Breakdown or Critique
Reflection
Idea or a plausible alternative
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5. Research Questions
RQ1:
For users working with static documents too large and detailed
to fit on their screen, controlling for the interfaces used, what is
the relationship between display techniques, type of task and
user experience (efficiency, effectiveness & satisfaction)?
RQ2:
For users working with dynamic information stream too
complex to be perceived at a single resolution of the screen,
controlling for the interfaces used, what is the relationship
between display techniques, type of task and user experience
(efficiency, effectiveness & satisfaction)?
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6. The Workflow
Derive realistic tasks Laboratory Laboratory
Field Work
for controlled Study on Static Study on
experiments Documents
Interview 14 Dynamic Views
multi-scale • Board task– • 12 participants
document users verifying • 8 participants
• 3 display
covering all five connections on a • 2 display
techniques ( f techniques ( f +
classes of activity. circuit board + c, o + d, z + c, o + d)
• Map task – finding p) • 1 task
a closest hotel on a • 2 tasks
map
• Driving
simulation task–
avoid nails on the
road and falling
rocks while driving.
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7. Study 1: Hypotheses
• H1: Subjects would complete each task faster
with the f + c interface than with the z + p
interface. (one-tailed hypothesis)
• H2: Subjects would complete each task faster
with the f + c interface than with the o + d
interface. (one-tailed hypothesis)
• H3: Subjects would report higher satisfaction
with the f + c interface than z + p and o + d
interfaces. (one-tailed hypothesis)
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8. Study 1: Method details
Participants– 12 Xerox PRAC employees.
No descriptive statistics of the sample? Was gender controlled? How
about subjects’ experience with any of the display techniques or any of
the tasks?
Independent Variables– Display Techniques (3 levels) and type of tasks (2
levels)
Dependent Variables– User Experience operationalized as time on task,
accuracy in performing tasks and self reported questionnaire (adapted
from QUIS)
No clear definition of the measures other than the questionnaire. How was
accuracy in performing tasks measured? What constitutes an error?
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9. Study 1: Method details (contd..)
Research Design– 3 (Display techniques) X 2 (task types)
Map Task Board Task
z+p
Two Factors f+c
o+d
Data Analysis– Two-way repeated measures ANOVA
When we carry out our experimental manipulation with same people, the
within-participant variance is made up of = the effect of manipulation +
individual differences in performance.
We have three experimental conditions for display techniques. But since no
corrected F-value is reported it is assumed that the data did not violate the
assumption of sphericity (Mauchly’s test was not significant).
Sphericity refers to the equality of variances of the differences between
treatment levels.
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10. Study 1: Results
Graphing the means
Average Task completion times in seconds
700
• Effect of display type Mean time on task
600
• No visible effect of 500
task type 400
• No visible interaction 300 Map Task
effect 200 Board Task
100
0
z+p f+c o+d
Display Technique
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11. Study 1: Results (contd..)
Source Type III df Mean F Sig.
sum of Square
squares dfM
Display Type Sphericity assumed 2 19.78 .000
Error (Display Type) Sphericity assumed 22 dfR
Task type Sphericity assumed 1 2.63 > .05
Error (Task type) Sphericity assumed 11
Display * Task Sphericity assumed 2 1.76 > .05
Error (Display * Task) Sphericity assumed 22
Test of within subject effects (Plausible table)
Two factors: display type and task type
One effect: Completion time
Display type has a significant effect on task
completion times.
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12. Study 1: Results (contd..)
Source Type III df Mean F Sig.
sum of Square
squares dfM
Display Type Sphericity assumed 2 2.23 >.05
Error (Display Type) Sphericity assumed 22 dfR
Task type Sphericity assumed 1 3547 .000
Error (Task type) Sphericity assumed 11
Display * Task Sphericity assumed 2 .60 > .05
Error (Display * Task) Sphericity assumed 22
Test of within subject effects (Plausible table)
Two factors: Display type and task type
One effect: Task accuracy
And how do we measure that?
Task type has a significant effect on task
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13. Study 1: Results (contd..)
Source Type III df Mean F Sig.
sum of Square
squares dfM
Display Type Sphericity assumed 2 9.30 .000
Error (Display Type) Sphericity assumed 22 dfR
Task type Sphericity assumed 1 0.011 >.05
Error (Task type) Sphericity assumed 11
Display * Task Sphericity assumed 2 0.97 > .05
Error (Display * Task) Sphericity assumed 22
Test of within subject effects (Plausible table)
Two factors: Display type and task type
One effect: User Satisfaction
Display type has a significant effect on user
satisfaction.
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14. Study 1: Results (contd..)
Source Display type Task type Type III df Mean F Sig.
sum of Square
squares dfM
Display Type o + d vs. f + c 1 19.54 .000
z + p vs. f + c 1 36.52 .000
dfR
Error o + d vs. f + c 11
z + p vs. f + c 11
Test of within subject contrasts (Plausible table)
Two factors: display type and task type
One effect: Completion time
f + c yielded faster completion times than
both the other display types.
Planned contrasts also suggested: f + c was favored for user satisfaction over other
two displays as well as for easier orientation to the displays.
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15. Study 1: Discussion
• Switching effort was found to be the major factor to influence the
experience of an interface.
• Problems rose like blurriness of projection and shadow casting.
• Multivariate analysis with all the dependent variables.
• Control for gender.
• Better operationalization of the measures.
• Report Effect Size: (More so, when it is this large)
F(1, dfR )
r=
F(1, dfR ) + dfR
• ro + d vs. f + c = 0.79 and rz + p vs. f + c = 0.88 (Very Large Effect Sizes)
• Given the options, maybe a between-group design is not a good
idea. With N = 12 in each of the 6 (3 X 2) conditions, we get dfR as
6 X 11 = 66. The critical F-value required for significance (p <
.001) also decreases, but at the loss of the effect size.
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16. Study 2: Hypotheses
• H1: Subjects in the car task would produce lower
error rates when using f + c interface compared to o
+ d interface. (one-tailed hypothesis)
• H2: Subjects would ne more satisfied using the f + c
interface for the car task than the o + d interface.
(one-tailed hypothesis)
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17. Study 2: Method details
Participants– 8 Xerox PRAC employees. (subset of previous participants)
Won’t using the same people cater to additional change for the previous
experimental manipulation? No descriptive statistics of the sample? Was
gender controlled?
Independent Variables– Display Techniques (2 levels) and collision type (2 levels)
Dependent Variables– User Experience operationalized as accuracy in performing
tasks and self reported ranking for the preferences of the interfaces.
Why user efficiency was not measured? Time on task?
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18. Study 2: Method details (contd..)
Research Design– 2 (Display
techniques) X 2 (collision types)
f+c o+d
Run-over nails
Rocks hit
Two Factors
Data Analysis– Two-way repeated measures ANOVA
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19. Study 2: Results
Graphing
Mean number of collisions subjects caused in the car task the means
25
Number of errors
• Effect of display type 20
• More number of errors 15
for collision with nails, so
10 Run over nails
effect of collision type.
• No visible interaction 5 Rocks hit
effect 0
o+d f+c
Display type
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20. Study 2: Results (contd..)
Source Type III df Mean F Sig.
sum of Square
squares dfM
Display Type Sphericity assumed 1 843.5 .000
Error (Display Type) Sphericity assumed 7 dfR
Collision type Sphericity assumed 1 19.71 <.01
Error (Task type) Sphericity assumed 7
Display * Collision Sphericity assumed 1
Error (Display * Collision) Sphericity assumed 7
Test of within subject effects (Plausible table)
Two factors: display type and collision type
One effect: Errors
Both collision type and display type has a
significant effect on task accuracy.
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21. Study 2: Discussion
• Also users reported higher satisfaction (significant) with f + c
interface than o + d interface.
• Better performance in f + c may be because of the use of the
peripheral vision.
• Did not report effect size
• Is it because o + d interface had two different screens that
hindered peripheral vision? Was the overview screen in the
optimal range of peripheral vision for the users? The f + c
interface was overall larger in size. Was it creating an
immersion effect on playing the game?
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22. Connecting the dots..
• Two controlled experiments provided evidence of better
performance of f + c interfaces for navigating static and
dynamic multi-scale documents.
• Authors claim that these results suggest that f +c screens
can enable individuals to carry out monitoring + interaction
tasks that are now typically done by a team of at least two.
Sounds a little ambitious. No baseline performance
evaluation with group of users were done in the study.
• No questions were asked to users to understand the effects
of low-res context screen (f + c) compared to high-res
overview (o + d). Did it predict the errors in f + c interfaces?
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23. Thank you
Questions?
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