Information Technology Reference
In-Depth Information
Table 8.9 shows data for eight tasks in a usability study of a website. For
each task, a target number of page visits has been predetermined (ranging from
4 to 10). Figure 8.6 depicts the target and actual page views for each task graphi-
cally. This chart is useful because it allows you to visually compare the actual
number of page visits for each task, and its associated confidence interval, to the
target number of page views. In fact, all the tasks had significantly more page
views than the targets. What's perhaps not so obvious is how the various tasks
performed relative to each other—in other words, which ones came out better
and which ones worse. To make that kind of comparison easier, Figure 8.7 shows
the ratio of the target to actual page views for each task. This can be thought of
as a “page view efficiency” metric: the closer it is to 100%, the more efficient the
participants were being. This makes it easy to spot tasks where the participants
had trouble (e.g., Task 3) versus tasks where they did well (e.g., Task 7). This
technique could be used to represent the percentage of participants who met
any particular objective (e.g., time, errors, SUS rating) either at the task level or
at the overall level.
Actual Page Visits Compared to Target Visits
Task 8
Task 7
Task 6
Task 5
Task 4
Task 3
Task 2
Task 1
0
2
4
6
8
10
12
14
Actual # of Page Visits Target # of Page Visits
Figure 8.6 Target and actual number of page visits for each of eight tasks. Error bars represent the 90%
confidence interval for the actual number of page visits.
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