Use anthropometry data to help design a rough prototype,
mock-up or buck. Often it helps to make it adjustable.
Choose some testers (perhaps simply colleagues, students
or family) who are very large or very small in the dimensions
which matter for usability. Match your users' age if flexibility
is relevant.
If you have PeopleSize in your
department, use the Measurements TO percentiles facility
(access is from the main output dialog) to find out exactly
what percentiles these testers are in all the relevant dimensions.
Otherwise, your tutor will show you how to work these out
manually. If necessary, find extra testers to get exact
percentiles, or particular combinations, for important dimensions.
Have your testers mimic real-life use of your design, and
record what difficulties, clearances, reaches etc. they
have. Record what you observe not what they say, and take
formal numerical measurements. You may have to correct some
habituated postures, e.g. splayed knees among tall drivers.
Make adjustments, or tailor the design, until the best fit
is achieved within your other constraints.
Record what percentiles are accommodated by the improved
design, and explicitly consider the consequences for users
who cannot be accommodated - safety? discomfort? extra instructions?
can you stop them buying/using?
Remember that exclusions accumulate: 95th percentile fit
for three different dimensions can exclude up to 14 percent
of the intended user group (see People Percentiles in the
PeopleSize Professional page).
Make a record of your usefully-sized testers, for the future
(PeopleSize users can use the Export
facility).
