Siguccs20101026

Comparing a Video Projector
and an Inter-PC Screen
Broadcasting System in a
Computer Laboratory
Takashi Yamanoue, Koichi Shimozono,
Kentaro Oda
Kagoshima University

Contents
1. INTRODUCTION
2. OUTLINE OF THE USABILITY TESTING
3. OUTLINE OF SOLAR-CATS
4. THE EXPERIMENT AND ITS RESULT
5. EXPERIENCES
6. RELATED WORKS
7. CONCLUDING REMARKS

1. INTRODUCTION
 Presentation tools in a Computer Lab.
Video projectors
Inter-PC screen broadcasting systems
…
 When designing the Lab,
What kind of ?
How many
 We would like to have some benchmarks of
presentation tools.

 Experimental benchmark
 A Usability testing procedure
 Compared cognitive effects on users
A video projector
 An inter-PC screen broadcasting system

 Quantitative results
 of presentation tools' cognitive effects on users'
cognition ability.

 The usability testing
 Repeat
A sample text -> Subjects, using a target tool
 Subjects type
 Record Typing speed and its accuracy

 SOLAR-CATS
 A computer assisted teaching tool
 The text editor
 User activity recorder

 The result
 The projector was better
 if there was small amount of data on one screen
 The screen broadcasting system was better
 if there was a large amount of data on one screen.

2. OUTLINE OF
THE USABILITY TESTING
 A way of measuring effects of target
presentation tools
 collect the results of tests on cognition of
subjects (who are supposed to be the audience or students)
after the same materials were shown
 (to the subjects)
inthe same environments
using such different target tools.

 It is not a fair comparison
 to show the same materials
 to the same subject using a target tool
 after showing the same material to the same
subject using another target tool
 because the subject can remember the
material previously shown.

 A solution
 The sample text 1 of difficulty 1
-> Subjects(1,2,…n)
 usingthe target tool 1
 Subjects type

 The sample text 2 of difficulty 1
 usingthe target tool 2
 Subjects type

 …

 …
 The sample text k of difficulty l
 usingthe target tool j
 Subjects type

 The sample text k+1 of difficulty l
 usingthe target tool j+1
 Subjects type

 …

 Typing speed and its accuracy
 Effect
 on the subject Mi
 showing the k th sample text Lj,k,l
of difficulty l
 Using the target tool j

 E(Mi,Lj,k,l)
or
 Result Ri,j,k,l (=E(Mi,Lj,k,l))

 for(l=1; l<s; l++){
 for(k=1; k<r; k++){
 for(j=1; j<m; j++){
 Show the material Lj,k,l using the tool Tj
to the set of subjects A={M1, …, Mn};
 All of subjects test for cognition of Lj,k,l;
 Collect Ri,j,k,l (=E(Mi,Lj,k,l)); }
 Rest-1, a term of rest;
 }
 Rest-2, a term of rest;
 }

 Information conductivity
 To the i th subject
 From the j th target tool
 Of the k th sample text of difficulty l

 How fast and how precise the i-th subject
typed the Lj,k,l when j-th tool is used.
 Ri,j,k,l

 Multiplication of
 Average speed of typing of the sample text
 Precision (1- Error rate)

 Ri,j,k,l=Avi,j,k,l(1-Aerri,j,k,l)
Letters/second

 R*,j,*,l
 Theaverage values of Ri,j,k,l in the
experiment
Where j-th target tool is used and
The materials were l-th difficulty.

3. OUTLINE OF SOLAR-CATS
 A WYSIWIS (What You See Is What I See)
 Enables sharing real-time operation of
 Applications
 text editor
 draw
 a simple programming environment
 web browser
 writer’s assistant , …

 All equipped with SOLAR-CATS.

 Consists of
 node systems (nodes)
 a group manager.

 Each node system
 Applications
 A main controller
 A command transceiver
 An event recorder/player

Group Manager

Teacher’s node system

TCP TCP Student’s node
Student’s node system
system

TCP
TCP TCP TCP

Student’s node Student’s node Student’s node Student’s node
system system
system system

Writer’s Assistant

Web Browser
Programming Environment

Text Editor

Draw

Applications

Main Controller Command Event Recorder/
Transceiver Player

Network

4. THE EXPERIMENT AND ITS
RESULT
 Image broadcasting function of SOLAR-CATS
VS.
 The video projector
 hung from the ceiling of the laboratory.
 Brightness of the projector : 5000 lm
 Size of the screen: width 2m45cm, height
1m84cm
 Distance from the screen to the projector: 5m

 Distance from the screen to the subject at the
most far side: 5m 50cm
 Position of the projector from the subjects: Left
side or right side from the subjects.
 Distance from the floor to the lowest side of the
screen: 92cm
 Ceiling lights for the screen were turned off.
 All other ceiling lights were turned on.

 Sample texts
 Power point slides of Japanese sentences
 The difficulty of materials was the number of
letters on one slide.
2 kinds of difficulties (s=2)
 30 letters total, 3 lines and 10 letters in one line.
The size of a letter was 72 point.
 120 letters total, 6 lines and 20 letters in one
line. The size of a letter was 36 point.
 6 sets of the above slides (sr=6)

 82247:o-drawing fc(0).mm(180,430)
 82434:o-drawing fc(0).mxit(173,428)
…
 99219:m-tedit txtedit.txt.kty(0,0,26085)
 99219:m-tedit txtedit.txt.kty(0,1,26412)

j=Video Projector j=SOLAR-CATS

l=1, R*,j,*,l=1.36 R*,j,*,l=1.17
30
letters (std. 0.58) (std. 0.39)

l=2, R*,j,*,l=1.04 R*,j,*,l=1.17
120
letters (std. 0.38) (std. 0.32)

 Conductivity of projector is better
 if the number of letters was smaller
 Conductivity of SOLAR-CATS is better
 if the number of letters was larger.
 Standard distributions of the projector were
larger than that of SOLAR-CATS.
 It might say that the conductivity of the
projector is affected by the subject’s position.

5. RELATED WORK
 Quantitative evaluation of a GUI
 has been studying as a research of usability for
many years.
 Survey and usability testing are used for this
evaluation[5].
 Our experiment can be considered as one of
usability testing.

 Full-dress usability testing
 A usability laboratory, monitors and usability
engineers
 Much money and time

 Nielsen, J.
 Easy ways of usability testing
 Five subjects are enough.
 If qualities of subjects is not so distributed
 Our experiment
 has no problem for the number of subjects
 in this sense.
 Automate some of observation of test and
marking the test using tools such like SOLAR-
CATS.

 KLM (Keystroke-Level Model)
 Can be used by individuals or companies
seeking ways to estimate the time it takes to
complete simple data input tasks using a
computer and mouse[2].
 Our experiment uses a kind of KLM.
 SOLAR-CATS was used to obtain some values of
KLM.

 Aoki and others
 A system which records and replay operations
of a Web client.
 KLM using the system with an editor on a Web
page
 Does not have the function which broadcast
images and operations to many clients in a
short time.
 On the other hand, SOLAR-CATS has the
function.

 Nishida and others
 Collected keystroke interval data of daily usage
at computer laboratories of a university[6].
 The data of computer laboratories was better
than the data of the controlled experiment.
 Our experiment was a controlled experiment
this time. It is not so difficult to collect the data
of daily usage using SOLAR-CATS.

 Tamura
 An optimum letter size and an optimum space
between lines of texts
 which are displayed on an electronic chalk
board for distance learning environment[7].
 He has used a survey to obtain the results while
we have used usability testing. In other words,
his test is a subjective test and our test is an
objective test.

 Kiyohara and others
 Understandability of printed materials are better
than that of materials on an LCD or a CRT.
 Similar to our procedure.
 Used test sheets which ask yes or no answer
about contents of materials to subjects.
 It requires much money or time in order to
prepare the test sheets.
 Our experiment does not require test sheets.

6. CONCLUDING REMARKS
 A usability testing of presentation tools for
computer laboratories
 Compared a video projector and inter-PC
broadcasting system
 SOLAR-CATS is used
 as the inter-PC broadcasting system
 It is also used for recording the experiment.

 The results were in our common knowledge.
Not new…
 However, we could have Quantitative
results.
 Would like to have more precise results.

7. Acknowledgement

 We thank our students who are subjects of
the experiment and help us to develop and
test SOLAR-CATS.
 A part of this work was supported by Grant-
in-Aid for Scientific Research of Japan
Society for the Promotion of Science,
Fundamental Research(C), 17500041.

Siguccs20101026

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