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Wireless Sensor and Actuator Networks for Lighting Energy ...

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(5) At the 20 th minute, the test ends. The participants are debriefed <strong>and</strong> interviewed,<br />

<strong>and</strong> their questionnaires are collected.<br />

The post-test interview is intended to gather feedback beyond the questionnaire<br />

<strong>and</strong> to identify reasons <strong>for</strong> any unanticipated behaviors. The interview basically<br />

followed the script provided in Appendix B.8. Some of the questions were very similar<br />

to the questions in the in-test questionnaire to encourage criticism of either system <strong>and</strong><br />

to ensure that important research questions were asked. This experiment lasted<br />

approximately 60 minutes: 5 minutes <strong>for</strong> instructions <strong>and</strong> questions, 20 minutes <strong>for</strong> each<br />

working set, 5 minutes <strong>for</strong> debriefing <strong>and</strong> interviewing, <strong>and</strong> 10 minutes <strong>for</strong> the<br />

intermission in between the two sessions.<br />

8.4.3 Results <strong>and</strong> Discussion<br />

Preferred manual overriding mechanism<br />

Three aspects of the two manual overriding mechanisms were evaluated through<br />

the questionnaire: (1) easiness of learning the mechanisms, (2) easiness of overriding<br />

the lights with the mechanisms, <strong>and</strong> (3) preference <strong>for</strong> the mechanisms. The<br />

participants’ opinions were quantified using a five-level scale in the questionnaire:<br />

totally agree, partially agree, neither agree nor disagree, partially disagree, <strong>and</strong> totally<br />

disagree. The results are summarized in Table 8-2, where the options of totally agree<br />

<strong>and</strong> partially agree are assigned in the same category, <strong>and</strong> so are those of totally<br />

disagree <strong>and</strong> partially disagree. The detailed answers to each question can be found in<br />

Appendix B.3.<br />

136

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