Deciding What Data to Collect
There are two types of data:
- Process data are observations of what the test users are
doing and thinking as they perform the task.
These data tell you why actions are happening.
Process data are collected during
thinking aloud tests.
- Bottom-line data give a summary of what is
happening: how long do users take over each step; are they successful;
how many errors do they make, etc.
Bottom-line data are collected through logging.
Normally you will want to collect process data first:
you first need to know why users make certain choices,
so you can improve the interface to reduce error rates;
afterwards you can collect bottom-line data to measure exactly
how well (or poorly) users perform.