It is helpful for questionnaire writers to have a toolbox of key issues to consider when constructing rating scales. Here is a toolbox:
1. What do you want to measure (e.g., likelihood, interest, satisfaction, or something else)? Consider how people think about the topic of interest and what information you really need.
2. Should you use a unipolar or bipolar scale? Think about whether the dimension you are scaling has a natural opposite and whether you need to capture information from the opposite end of the spectrum.
3. What will be the length of the scale (e.g., 5 points, 7 points, or some other length)? Think about how many levels people actually have in their heads, how many items you are asking respondents to rate, and how much effort you can expect respondents to invest.
4. If you have a bipolar scale, should you provide a midpoint? Does it make sense to force respondents toward one side of the scale or the other?
5. Will you label only the endpoints or also all of the middle points between the endpoints? Think about practical issues, such as how the survey will be administered and the amount of space available on paper or screen. Also consider whether respondents will understand a numbered scale without labels for the middle points between the endpoints.
6. What will you call the endpoints (e.g., very satisfied and very dissatisfied, or extremely satisfied and extremely dissatisfied)? If you name the middle points, what will you name them?
What else might you think should be in the scaling toolbox?