INTERACTION D ESIGN
1 Evaluation: Introduction W HY , WHAT , WHERE AND W HEN TO
Design and Evaluation happen iteratively
one after the other.
Why: to check that users can use the product
and that they like it.
What: a conceptual model, early prototypes of
a new system and later, more complete
Where: in natural and laboratory settings.
When: throughout design; finished products
can be evaluated to collect information to
inform new products. 2 B RUCE TOGNAZZINI ON E VALUATION
“Iterative design, with its repeating cycle of design
and testing, is the only validated methodology in
existence that will consistently produce successful
results. If you don’t have user-testing as an
integral part of your design process you are going
to throw buckets of money down the drain”
See AskTog.com for topical discussions about
design and evaluation. 3 BASIC EVALUATION TECHNIQUES
4 E MPIRICAL E VALUATION
Relies on observations from real use/exhibition of
the prototype or model.
Two main categories:
Usability Study (also: user study, usability testing,
In a controlled lab environment to test usability aspects
(e.g. efficiency, effectiveness of interface)
In the field to test appropriation of the interface (i.e.
whether users will use it in their lives.
5 A NALYTICAL E VALUATION
Does not include observations from the
field but arguments based on models
(e.g. mathematical) or expert opinion.
Heuristic Evaluation, Walkthroughs
(Cognitive Walkthroughs, Pluralistic
Predictive Models: 6
GOMS, KLM, Fitt’s Law E VALUATION P URPOSES
Evaluation that takes place during design to
check whether it continues to meet the users’
needs (while more design is happening).
Evaluation that takes place in the end of the