Experiment

Introduction

The goal of the vacuum pump system software is to help user understand how the technology makes it works. The system can achieve low pressures by allowing the user to change the system actuators. It also allows the user to see the outputs immediately on the pressure displays. Two interfaces are included in this software -- Simple and VisSim. The Simple is actually communicating with the VisSim after it starts. The Simple is running on the screen while the VisSim is running on the background.

Hypothesis

Users using the Simple will be able to bring the pressure down faster than users who only have VisSim, because they are more likely to learn and operate the system rapidly. The graphics on Simple makes the users understand the manufacturing process "easier", it can help users operate the simulation faster, learn the behavior of the system easier and better.

Independent Variables

There were two independent variables, the VisSim (figure 1) and Simple (figure 2) interfaces. Some subjects were given the VisSim first while the other given the Simple first. We did it this way so that the performances of the subjects could be more analyzable.

Dependent Variables

There were two dependent variables, the complete time and subjective preference. The complete time was measured in seconds from the beginning of the task until the chamber pressure reached a horizontal line. The subjective preference was told by the subjects and also measured with the ease of use, clearing of the features, labels, etc.

Pilot Test Results

• Some of the subjects were not able to completet the task 2 correctly using Vissim or Simple Interface. Most of the subjects found it very difficult to remember the steps. (Write down steps on the next experiment)
• In Vissim, most subjects clicked on the wrong button for the Mechanical pump. There were two buttons for mechanical pump, one button which was accidentally clicked most of the time which links to mechanical pump and four other devices. The other button links only to the mechanical pump, which was the button that the subject supposed to click. (Warn Subject about it on the Next Experiment)
• Procedures for the subjects were confusing. (clarify the procedures for the subjects on next the Experiment)
• Most subjects believed that Simple was clear and Vissim was very hard to understand.
• Some subjects complained the labels in Vissim were not clearly labeled out.
• All the subjects in the pilot Study prefered Simple as their first choice to use.
• The simulation parameters for Vissim were not changed. The experimenter thought by changing the simulation parameters on Simple, it should reflect to the Vissim. (Before the next experiment, experimenter will find out how to change the simulation parameters on Vissim.)
• In Simple, the subject didn't know what C, T, and M stand for on pressure history graph. C - Chamber pressure, T - Turbo Pump pressure, and M - Mechanical pump pressure. (On the next experiment, it will be covered to the subjects.)
• Some subjects said that Simple was easier for learning.
• Instructions to the subject should be more clearer. (Give step by step instructions and make it more clear to the subject, so the subject will have the correct way of doing the tasks)

Subject Resource

Ten students of the University of Maryland at College Park participated in the experiment. The subjects were majoring in engineering and computer science. The lab experience with pump system of subjects from no experience to some experience. The hours of computer used per week of subjects from less than 5 to more than 10.

Materials

The interfaces used in the experiment were Simple and VisSim. Both interfaces were installed in 17" Gataway 2000 monitors in HCIL. A timer programmed with Visual Basic was set at the top of each interface. Other materials used in the experiment were record sheets used by experimenter, subject's tasks sheet, background surveies, free text description sheets and questionnaires.

Experiment Procedures

1. Greets the subjects and explain the goal of the project. (Tell subject we're testing the interfaces and not them.)

2. Have the subject signed the consent form.

3. Have the subjects filled out the background survey.

5. Hand out the subject a practice tasks list with step by step instructions. Practice Simple Tasks.or Practice Vissim Tasks.

6. Subject practices with either Vissim or Simple until he/she is comfortable with it. (3-10min) .

7. Record Practice Time. Observe and write comments of the subject's reaction to the interface

8. When each subject finished the tasks, give the subject a free text description.

9. Take the practice tasks away and give them actual tasks without the step by step instruction. Actual Simple Tasks or Actual Vissim Tasks.

11. Record Task completion Times for both interfaces. Observe and write comments of the subject's reaction to the interfaces

12. Give them five minutes to explore the other interface.

13. Have the subjects filled out the questionnaire.

14. Thanks subjects.

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