Jared is correct in saying that you don't have all of the information necessary to calculate how many people you should interview, but I would put forward one caution about the approach proposed by Jared:
If you know that you have a user segment that is relatively scarce, but important for you to capture - like your executive team, for example - you should be certain to include a representative of this group in your studies. Essentially you're adopting a stratified sampling technique rather than a purely random sample as a deliberate tactic to cover small audience groups. Best Regards Steve 2008/7/14 Jared Spool <[EMAIL PROTECTED]>: > Hi Elizabeth, > > The answer is quite simple. It's very easy to calculate how many folks to > observe and interview to ensure you've learned everything you need to learn. > > The only problem is, you can't make the calculation until you've already > done all the observations and interviews. You just don't have the necessary > information to do the calculation. :) > > Short of that, you want to conduct your observations until you reach what > we call, "the point of least astonishment." This is the point where, in each > subsequent session, you're only seeing things you've seen before. > > Reaching this point means you have everything you need to build your > personas. Until you reach this point, you won't know for sure if you've left > something important out. > > The good news is that it probably doesn't matter too much. While you can > make great strides with the initial design, improving efficiency can't be > done with only a single release. It has to be done incrementally. > -- ---------------------------------------------- Steve 'Doc' Baty B.Sc (Maths), M.EC, MBA Principal Consultant Meld Consulting M: +61 417 061 292 E: [EMAIL PROTECTED] UX Statistics: http://uxstats.blogspot.com Member, UPA - www.upassoc.org Member, IA Institute - www.iainstitute.org Member, IxDA - www.ixda.org Contributor - UXMatters - www.uxmatters.com ________________________________________________________________ Welcome to the Interaction Design Association (IxDA)! To post to this list ....... [EMAIL PROTECTED] Unsubscribe ................ http://www.ixda.org/unsubscribe List Guidelines ............ http://www.ixda.org/guidelines List Help .................. http://www.ixda.org/help
