To Matthew, good point that five may be too few. The concept is that each member of the design team should explore five sketches, which I found to be a workable maximum before reusing too many elements from previous designs. A team of five people, from project manager through module X programmer, would provide twenty-five sketches to review.

However, there is nothing to stop someone comfortable with the concept from designing ten, or even a hundred, radically different sketches. If you have a member like that on your team, then they need to go into business for themselves! If you are a member like that, I need to speak with you!

Cheers.

I don’t understand how 5 is chosen as the key minimal number of multiples to explore.

Nielsen suggests that with usability evaluations testing with 5 people gets the best return on investment (http://www.useit.com/alertbox/20000319.html) but a usability evaluation is uncovering a finite number of issues, design ideation is really exploring an infinite design space.

Your distinction between “versions of the same sketch” and a ‘real’ multiple is spot on! But I think you’ve glossed over how difficult it is to come up with actual ‘real’ multiples. As a professional I think I have some skill and techniques that I draw on to help me with this, but I still find it a challenge!

I like to use participatory design techniques to involve ‘non-designers’ into a design process, but I use sketching here to help them imagine possibilities they might not have imagined otherwise - I never expect them to be able to actually produce directly useful designs.