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

Contents

1. INTRODUCTION2. OUTLINE OF THE USABILITY

TESTING3. OUTLINE OF SOLAR-CATS4. THE EXPERIMENT AND ITS

RESULT5. EXPERIENCES6. RELATED WORKS7. 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)in the 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) using the target tool 1 Subjects type Record Typing speed and its accuracy

The sample text 2 of difficulty 1-> Subjects(1,2,…n)

using the target tool 2 Subjects type Record Typing speed and its accuracy

…

つぎの手順をわかりやすく…

… The sample text k of difficulty l

-> Subjects(1,2,…n) using the target tool j Subjects type Record Typing speed and its accuracy

The sample text k+1 of difficulty l-> Subjects(1,2,…n)

using the target tool j+1 Subjects type Record Typing speed and its accuracy

…

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 The average values of Ri,j,k,l in the experimentWhere 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

TCP TCP TCP TCP

Student’s nodesystem

Student’s nodesystem

Student’s nodesystem

Student’s nodesystem

Student’s nodesystem

Student’s nodesystem

Writer’s Assistant

Web Browser

Programming Environment

Text Editor

Draw

Applications

Main Controller Command Transceiver

Event Recorder/Player

Network

4. THE EXPERIMENT AND ITS

RESULT Image broadcasting function of SOLAR-

CATSVS.

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)

Examples of sample texts

Target tools

Recording data

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)

Results

j=Video Projector j=SOLAR-CATS

l=1,30 letters

R*,j,*,l=1.36

(std. 0.58)

R*,j,*,l=1.17

(std. 0.39)

l=2,120 letters

R*,j,*,l=1.04

(std. 0.38)

R*,j,*,l=1.17

(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.