If there is one thing I dislike, it is giving people advice about scales. As Brian Koma, our vice president of marketing puts it, "People will defend which scale they use like they're fighting a holy war."
So here's some advice on why the three-point scale, the five-point scale, the seven-point scale, the ten-point scale and the eleven-point scale are all the absolute best rating scale for you to use!
- Three-item scale: "Using only three answer options takes up a lot less visual space and is far less daunting than five options. Thus, we always try to limit the response options to three, as that number offers the robustness to capture what we need while still remaining visually inviting." - Ziggy Zubric, owner of Marketing Endeavors, "Less Really is More When it Comes to Response Scales"
- Five-point scale & seven-point scale: "To explore the relation between scale length and reliability, we conducted a meta-analysis of the results of many past studies. Our data consist of results from 706 tests of reliability taken from thirty different between-subject studies. We combined various measures of reliability and various sample sizes, controlling for these and other factors in determining the relation of scale length to reliability. In general, we found that five- or seven-point scales produced the most reliable results. Bipolar scales performed best with seven points, whereas unipolar scales performed best with five." - Jon Krosnick, professor of communication at Stanford, "The Optimal Length of Rating Scales to Maximize Reliability and Validity"
- Ten-point scale: "A five-point scale is totally inappropriate for customer satisfaction studies. Why? It lacks enough granularity and robs companies of a burning desire to take corrective action. It commonly leads executives to believe that ‘80% rate us four or five; that's great, let's move on,' without realizing that it simply means that 80% are at least somewhat satisfied. Further, many people will never rate anything a ‘five,' resulting in ‘four' including those who are really very satisfied and those who are only somewhat satisfied. To avoid this topping effect, use at least a 10-point scale and count nine and 10 ratings as fully satisfied. This will also allow easier analysis of what bottom-line effects satisfaction has, since such tools as regressions work better with a more granular score." - Brad Bortner, principal analyst with Forrester Research, "Best Practices: Why Customer Satisfaction Studies Fail"
- Eleven-point scale: "The 0-to-10 scale has many significant advantages: Customers find that the scale makes intuitive sense..., most of the world already uses the metric system..., customers may refuse to give anybody a perfect score..., customers will transpose the top and bottom on a 1-to-10 scale..., scales with fewer points seem more susceptible to grade inflation..., the 0-to-10 standard is being adopted by many of the world's leading companies." - Fred Reichheld, Fellow with Bain & Company, The Ultimate Question, p. 98-99
What's your favorite size for a rating scale, and why do you prefer it?