Refining the test phase of usability evaluation: how many subjects is enough?
Human Factors - Special issue: measurement in human factors
Finding usability problems through heuristic evaluation
CHI '92 Proceedings of the SIGCHI Conference on Human Factors in Computing Systems
A mathematical model of the finding of usability problems
INTERCHI '93 Proceedings of the INTERCHI '93 conference on Human factors in computing systems
Estimating the number of subjects needed for a thinking aloud test
International Journal of Human-Computer Studies
The evaluator effect in usability tests
CHI 98 Cconference Summary on Human Factors in Computing Systems
Proceedings of the second Nordic conference on Human-computer interaction
A Practical Guide to Usability Testing
A Practical Guide to Usability Testing
Comparative evaluation of usability tests
CHI '99 Extended Abstracts on Human Factors in Computing Systems
Testing web sites: five users is nowhere near enough
CHI '01 Extended Abstracts on Human Factors in Computing Systems
Analysis of strategies for improving and estimating the effectiveness of heuristic evaluation
Proceedings of the third Nordic conference on Human-computer interaction
Heuristic evaluation: Comparing ways of finding and reporting usability problems
Interacting with Computers
A comparative study of two usability evaluation methods using a web-based e-learning application
Proceedings of the 2007 annual research conference of the South African institute of computer scientists and information technologists on IT research in developing countries
Behaviour & Information Technology
Proceedings of the 5th Nordic conference on Human-computer interaction: building bridges
Consolidating usability problems with novice evaluators
Proceedings of the 5th Nordic conference on Human-computer interaction: building bridges
Undo and erase events as indicators of usability problems
Proceedings of the SIGCHI Conference on Human Factors in Computing Systems
Cultural cognition in usability evaluation
Interacting with Computers
Number of people required for usability evaluation: the 10±2 rule
Communications of the ACM
Cultural usability tests - how usability tests are not the same all over the world
UI-HCII'07 Proceedings of the 2nd international conference on Usability and internationalization
Relationship model in cultural usability testing
UI-HCII'07 Proceedings of the 2nd international conference on Usability and internationalization
HCI'07 Proceedings of the 12th international conference on Human-computer interaction: interaction design and usability
Cultural usability: the effects of culture on usability testing
INTERACT'07 Proceedings of the 11th IFIP TC 13 international conference on Human-computer interaction - Volume Part II
Towards the maturation of IT usability evaluation (MAUSE)
INTERACT'05 Proceedings of the 2005 IFIP TC13 international conference on Human-Computer Interaction
Sample size in usability studies
Communications of the ACM
Backtracking Events as Indicators of Usability Problems in Creation-Oriented Applications
ACM Transactions on Computer-Human Interaction (TOCHI)
Usability problem identification in culturally diverse settings
Information Systems Journal
Outliers in usability testing: how to treat usability problems found for only one test participant?
Proceedings of the 7th Nordic Conference on Human-Computer Interaction: Making Sense Through Design
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User effect in terms of influencing the validity and reliability of results derived from standard usability tests has been studied with different approaches during the last decade, but inconsistent findings were obtained. User effect is further complicated by other confounding variables. With the use of various computational models, we analyze the extent of user effect in a relatively complex arrangement of international usability tests in which four different European countries were involved. We explore five aspects of user effect, including optimality of sample size, evaluator effect, effect of heterogeneous subgroups, performance of task variants, and efficiency of problem discovery. Some implications for future research are drawn.