Test Goals
The type of usability test chosen depends primarily on the
goal of the test as well as the product's development stage. A
test can follow two goal strategies in the evaluation of the
product, and it is essential that the usability experimenters
decide before the test takes place as to the nature of their
evaluation. This is important as it becomes increasingly
difficult and disorderly if a dramatic shift is made in the goal
of the test while the test is taking place. While the tasks and
the features of the products can be changed around, it is
important that the primary goal of the test be either on
improvement of the product or comparing different alternatives.
- A formative evaluation helps in the improvement of
the product as part of an iterative design process. A
reliable technique for a formative format is the thinking
aloud procedure, that encourages the participant to speak
out their actions, thoughts and concerns while using the
product. The formative evaluations correspond with
exploratory, assessment, validation and comparison
usability test types.
- In summative evaluation, the overall quality of
the interface is assessed, with an emphasis on
quantitative measurement. This usually involves a test
between two or more alternatives for specific design
characteristics. Specific goals can be formulated to
address concerns in particular situations. Summative
evaluations correspond more with controlled experiments
that can be used to assess statistical differences
between strict quantitative measures of usability between
one product feature and another.
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