Hi, I ran a card-sorting experiment (free sorting) where I asked subjects to group a set of 100 items into groups of similarity. The subjects decided the number of groups they wanted to create. I am going to run cluster analysis to see the number of clusters that emerged from the data. I will then develop items to measure the groups that emerge. So essentially, the emerged groups are the constructs for my questionnaire.
I was asked how do I know I have enough sample size (i.e., participants) to feel comfortable with the result of the cluster analysis. I have checked several books on cluster analysis, none discusses the sample size issue. So, I would appreciate it if anybody can give me some pointers. Is there any rule of thumb governing the minimum number of sample size (i.e., subjects) required to run a cluster analysis? Any reference out there discussing this issue? Thanks.
