Andrew J. Ko

Associate Professor

The Information School

Computer Science & Engr. (adjunct)

University of Washington

Box 352840

Seattle, WA 98195

ajko | @ | uw | edu

Mary Gates Hall 015E

Chief Scientist + Co-Founder


Winter 2016
On sabbatical, learning things
Office hours by appt

Play Gidget, our new debugging game!

AnswerDash is a spinout of Parmit Chilana's work on LemonAid, serving instant contextual answers in web applications.

New NSF project! Variations to Support Exploratory Programming


While usability methods such as user studies and inspections can reveal a wide range of problems, they do so for only a subset of an application's features and states. FeedLack is a tool that explores the full range of web applications' behaviors for one class of usability problems, namely that of missing feedback. It does this by enumerating control flow paths originating from user input, identifying paths that lack output-affecting code. FeedLack was applied to 330 applications; of the 129 that contained input handlers and did not contain syntax errors, 115 were successfully analyzed, resulting in 647 warnings. Of these 36% were missing crucial feedback; 34% were executable and missing feedback, but followed conventions that made feedback inessential; 18% were scenarios that did produce feedback; 12% could not be executed. We end with a discussion of the viability of FeedLack as a usability testing tool.

Ko, A. J. and Zhang, X. (2011). FeedLack Detects Missing Feedback in Web Applications. ACM Conference on Human Factors in Computing Systems (CHI), May 7-12, Vancouver, BC, Canada, to appear. (acceptance rate: 25%)