
352 J. Goodman-Deane et al.
Figure 3. The percentage of the sample (froma 362 person survey)that would
beexcludedbya designthatis just usableat differentvisualacuities.This graph
was modified from one in (Goodman-Deane et al., in progress).
be used to calculate the proportion of a population that would not have the level of
visual acuity required by a product feature and thus would be excluded from its use
(Keates and Clarkson, 2003).
The graph in Figure 3 was constructed using this method with data from a survey
of 362 participants in the UK (Clarkson et al., 2012; Tenneti et al., in progress).
It thus gives the proportion of the sample that would