1
Number of Scale Categories
There is no single optimal number — traditionally, scales with five to nine categories are used.
More categories capture finer differences — but most respondents can only handle a few categories.
Involvement & Knowledge
morewhen respondents are interested in the rating or have deep knowledge of the object.
Nature of the Objects
morewhen fine differences are characteristic of the objects.
Mode of Data Collection
fewerin telephone interviews, where scales are harder to keep track of.
Data Analysis
fewerfor aggregation & group comparisons · morefor sophisticated, correlation-based statistics.
