Hi. When applying this formula to determine the number of pairs questions, I am curious to know how much can we deviate from that ideal number before we lose integrity of the data.
N = number of attributes
n = total number of levels across all attributes
In a current example, this formula yields a number which makes our survey very long. In order to shorten the survey we could reduce the number of pairs questions but don't want to jeopardize capturing high-quality data.
Are there rules of thumb here? Thanks.