Moderating Usability Tests

88 CHAPTER 6 Interacting during the session

earlier, such statements can bias the test by infl uencing the partici-

pant’s perception of the usability of the product. It would be better

to just say, “Remember, don’t blame yourself when there isn’t time

to fi nish a task.”

6.6.7 Measuring assists

It’s beyond the scope of this book to discuss the measurement of

usability. But we do want you to recognize that counting assists can

be complicated. You can see from our discussion that all assists are

not the same and that the decision about providing assistance depends

on a number of factors. So it’s not easy to decide whether providing

an assist equals ...