Current Topics in HCI - Winter Semester 2004/2005

In this assignment, you will experience (or not) for yourself the joys of incremental search.


Download Firefox 1.0 from mozilla.org. It is available for Windows, Linux and Mac OS X.

Incremental search on a webpage is enabled by pressing the "/" key. Text you type after that will be searched incrementally. You can use ctrl/cmd-g to jump to the next match.

Lets take the following scenario: you want to find the cheapeast telephone rates for a local call on a Sunday using the service provided by heise.de.

After opening the main heise.de homepage, you would have to, using the mouse:

1. Click on the "Telefontarife" link on the left hand side.
2. Click on the "Einfache Preisübersicht" on the right hand side.
3. Click on the text field, type in your area code, click ok.
4. Click on "Samstag und Sonntag" link.

Using the keyboard with incremental search, the equivalent would be:

1. Type "/", followed by "telef", hit "Enter".
2. Type "/", followed by "einf", hit "Enter".
3. Hit "Tab" to move your cursor to the "Standort" text field, type in your area code, hit Enter.
4. Type "/", followed by "sams", hit "Enter".

Using a watch, time yourself (or a friend) performing the above scenario with the mouse and then with the keyboard about 3-5 times, until the times for the keyboard search have stablized.

Write a short summary of your results (one page is sufficient) with the following:

• Your timing data
• How long did it take before you (or your friend) got used to the keyboard interface? (if at all?)
• What is the difference in time between the fastest interaction with the mouse and the fastest interaction with the keyboard?
• Offer a simple (1 or 2 sentences) explanation for your results

For extra credit, do one (or more) of the following:

• Do a Student's t-test analysis of your data. Are the differences you observed statistically significant? What is the p-value?
• Suggest some improvements to the design of the incremental search feature in Firefox, based on Raskin's principles.
• Suggest some improvements to the design of Firefox in general, based on Raskin's principles.

You may work on your own or in groups of 2.


Hand in your submission before the end of the lecture on Thursday, November 18.

If you wish to submit your assignment electronically, email a PDF to This email address is being protected from spambots. You need JavaScript enabled to view it. before the due date. Please note that no other format (Word, OpenOffice, etc...) will be accepted. The subject of your email should be "CTHCI Assignment 4"; be sure to use this exact subject line as it will be used to filter assignment submissions for grading.


The assignment will be graded on the following rough scale:

• 1.0 - exceptional work that clearly went above and beyond what was expected from the exercise
• 2.0 - exercise was completed satisfactorily as per the assignment specification
• 3.0 - exercise was completed, but has some problems
• 4.0 - incomplete exercise
• 5.0 - little or no effort was put into the exercise

Late assignments will be graded with a penalty of 0.5 per 24 hour period after the due date.