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References 43

3. A spam filter assigns ratings to all incoming emails. If the rating of an email is
higher than a specific threshold, the email is deleted before it reaches the inbox.
Answer the following questions based on this scenario:
a. What is a Type I error in this scenario?
b. What is a Type II error in this scenario?
c. If the rating is assigned using a scale of 1–10, with 1 representing “definitely
not spam” and 10 representing “definitely spam,” what happens if the
threshold is set to 1, 2, 3, …, 10?
d. What do you think the appropriate threshold should be? Why?

REFERENCES
Accot, J., Zhai, S., 2003. Refining Fitts' law models for bivariate pointing. In: Proceedings of
the SIGCHI Conference on Human Factors in Computing Systems, pp. 193–200.
Bi, X., Li, Y., Zhai, S., 2013. FFitts law: modeling finger touch with Fitts' Law. In: Proceeding
of the SIGCHI Conference on Human Factors in Computing Systems, pp. 1363–1372.
Brewster, S., Chohan, F., Brown, L., 2007. Mobile interaction: tactile feedback for mobile
interactions. In: Proceedings of the SIGCHI Conference on Human Factors in Computing
Systems, pp. 159–162.
Chisnell, D., 2007. Where technology meets green bananas. Interactions 14 (2), 10–11.
Cohen, J., 1988. Statistical Power Analysis for the Behavioral Sciences, second ed. Academic
Press, New York.
Cooper, D., Schindler, P., 2000. Business Research Methods, seventh ed. McGraw Hill,
Boston, MA.
Durbin, C., 2004. How to come up with a good research question: framing the hypothesis.
Respiratory Care 49 (10), 1195–1198.
Feng, J., Karat, C.-M., Sears, A., 2005. How productivity improves in hands-free continuous
dictation tasks: lessons learned from a longitudinal study. Interacting with Computers 17 (3),
265–289.
Fitts, P.M., 1954. The information capacity of the human motor system in controlling the am-
plitude of movement. Journal of Experimental Psychology 47 (6), 381–391.
Kirk, R., 1982. Experimental Design: Procedures for the Behavioral Sciences, second ed
Brooks/Cole Publishing Company, Pacific Grove, CA.
Landsberger, H., 1958. Hawthorne Revisited. Cornell University, Ithaca, NY.
Lieberman, H., 2007. The tyranny of evaluation. http://web.media.mit.edu/~lieber/Misc/
Tyranny-Evaluation.html (retrieved 16.11.07.).
Macefield, R., 2007. Usability studies and the Hawthorne Effect. Journal of Usability Studies
2 (3), 145–154.
Mehra, S., Werkhoven, P., Worring, M., 2006. Navigating on handheld displays: dynamic ver-
sus static peephole navigation. ACM Transactions on Computer-Human Interaction 13 (4),
448–457.
Miniotas, D., 2000. Application of Fitts' Law to eye gaze interaction. In: Proceedings of the
SIGCHI Conference on Human Factors in Computing Systems, pp. 339–340.