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Yes, There is a Right and Wrong Way to Number Rating Scales

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Yes, There is a Right and Wrong Way to Number Rating Scales

Once we’ve identified a specific construct of interest, the question becomes; ‘how many scale points?’ There’s an easy way to decide.

All constructs are either bipolar or unipolar and the number of scale points we assign to a question depends on whether its hidden construct is bipolar or unipolar. Bipolar constructs are those where attitudes can fall on one side or the other of a midpoint that itself is true ambivalence or neutrality. For example, a school principal might want to know if parents think the school day is too long, too short, or just fine. Length, then, is a bipolar construct.

Unipolar constructs are those that lend themselves strictly to an amount–either there is the maximum amount of the attitude or none of it. For instance, let’s say I asked you to rate how helpful this article is. It may fall between being the most helpful article you’ve ever read and not helpful at all. From there, we can safely assume there is something in between–like “sort of” helpful.

So far that’s three response options that we can easily wrap our minds around. After that a response option in between the midpoint and the anchors is about all our brains can handle. Thus we are left with: Extremely helpful, Very helpful, Somewhat helpful, Slightly helpful, Not at all helpful–five scale points. While there is a “middle” point, the expression of that point is decidedly not synonymous with “neutral.”

Bipolar scales require seven scale points, three around each side of the midpoint–again a midpoint that truly means neutral, neither, or both.  If we go back to our school principal example, she would ask if the school day was: Much too long, Somewhat too long, A little too long, About right, A little too short, Somewhat too short, Much too short.

There has long been a ton of debate and confusion about scale point numbering. The academic scholarship has demonstrated that scales are most reliable when constructed with five and seven scale points.

Have questions on scale points or if the construct you are trying to measure is unipolar or bipolar? Ask away in the comments below.

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44 thoughts on “Yes, There is a Right and Wrong Way to Number Rating Scales

  1. Dan Hogan says:

    Should your choices be listed from negative to positive or just the opposite?

    1. Phil G says:

      Don and Paul–Indeed there is the possibility of primacy effects in questionnaires presented visually whereby people tend to favor the earlier response options. Stay tuned for our posts on avoiding order effects using flipping and rotation.

  2. Paul Therrien says:

    Hi Dan,
    There probably is no right or wrong answer. I would think that since our North American culture usually proceeds from left to right when reading, graphs are usually “0” on the left moving to more on the right, I would build my choices from negative to positive if it is an horizontal configuration and from positive to negative if the the configuration is vertical.

  3. Ian Pearson says:

    What is your opinion of the effect of not offering a mid point, say with 4 scale points? This potentially forces answers which demand either positive or negative atitudes

    1. Phil G says:

      Ian–Thanks for your question. There is no “midpoint” per se in a five point scale because its not “one side or the other,” but rather an amount. Think of the construct ‘likelihood’ where the middle option is actually something like a 50% likelihood—which in the case of rain, might cause you to bring an umbrella to work. In any case, it’s not ambivalence. As far as bipolar scales where there is a midpoint, you want to let people give an ambivalent answer if that’s what they mean, anything else introduces noise into the parts of the scale where true answers are.

  4. Linda says:

    Hi – Are you saying that a bipolar scale should be 7 points and not 5? How about:
    Very satisfied, somewhat satisfied, neither satisfied nor unsatisfied, somewhat unsatisfied, very unsatisfied.
    Is that bipolar? Suggestions for improving it? What about saying “neutral” instead of the middle mouthful?
    Thanks

  5. Michelle says:

    2 questions – we typically name rating scales rather than asking for a numerical rating as we believe this helps the respondent more accurately answer. But some clients also want an overall rating ‘out of 10’ so we then apply a weighting to all responses. Do you have any recommendations as to how to apply a 0-10 rating scale to a 5 point scale?

    further, there are clients that we know will more likely be rated highly on satisfaction scales. To increase granularity to results, rather than using a 7 point scale which we find too large and onerous, is it appropriate to have an ‘unbalanced’ scale such as dissatified, somewhat satisfied, satisfied, very satisfied, extremely satisfied. If so, then again we have difficulty in assigning a 0-10 rating later.

  6. Abid O says:

    Looking forward to responses on the 11-point Net Promoter recommend scale, of 0-10.

  7. Palle says:

    Actually science shows 10 point scales are to be preferred from a purely statistical view, because the data becomes less scewed.

    However how is it to just use a 5 point scale from “Complete disagree —> completely agree” and then leave a 6 = Doesn’t know,

    That way u can treat 6 as “missing value” in spss, or whatever. And 1-5 = a score.

    ?

  8. Teresa says:

    I want to measure frequency and importance of each item. Can I have two scales for the same item; each would be 5 points from 0-4.

    1. Anne R says:

      Hi Teresa–If you want to measure frequency and importance, creating two separate questions would be best. Each question would then have it’s own rating scale, which should be fully labeled (e.g. Extremely Important, Very Important, Moderately Important, Slightly Important, Not at all Important). Let us know if you have any questions or if we can help in any other way!

  9. Patrick says:

    What about rating scales? To compare different on-line lectures, if I ask for an overall rating, is it better to have a 0-10 scale, a 1-10 scale, or a 0-5 scale? I like 0-10 because people can get their head around base-10 numbers, like percentages.

    Thanks!
    Patrick

  10. once read about a “Net Promotor Score” concept as follows:
    After two weeks of the service provided from 1-10 with ten being the best,
    1. How likely is it that youb would rate “ABC Company” service or product to a friend or relative.
    2. Sort into three groups, 1)9-10=promotors 2)7-8=passive 3) 0-6 Detractors
    3.%of pormotors – % of Detractors = Net Promotor Score (N.P.S.)

    What are your thoughts on this process?

  11. JAL16 says:

    Do people use questions that allow the surveyor to provide additional free form comments or are the questions typically just the format that I’ve seen thus far in the examples? Like if there is a response for “other” then they can explain in detail? If so, how do you evaluate the responses?

  12. Michelle says:

    The main reason for my comment is to say I enjoy reading peoples comments. Comments to me are somewhat a helpful joyful therapy. I myself either like something, laugh to myself, walk away, or find a way to make it work for me.

  13. Gerry says:

    I’m constructing a survey for an organization around communication, culture, etc. It seems like the questions should be bipolar, but your question bank shows all these as unipolar. For example, it seems like I should ask: How effective is XX at communicating across the organization: Very Innefective, Somewhat Innefective, Neither Effective nor Innefective, Somwhat Efective, Very Effective. With a unipolar scale, there is only one negative response and four somewhat positive responses. Won’t that cause bias, and not be helpful in uncovering poor communication?

    1. Phil G says:

      Hi Gerry,

      Thanks for your question. The basic rule is that for most constructs, in-, dis-, un-, etc. do not automatically create cognitive symmetry. What is cognitive symmetry in simple terms? That is, the prefix does not immediately create an equally balanced antonym for the word of interest.

      For example, let’s use the construct of interest. It isn’t possible to have less than ‘no’ or ‘zero’ interest. Therefore, uninterested isn’t the opposite of extremely interested, very interested, somewhat interested, or slightly interested.

      Hope this helps.

      Phil

  14. Hi there! I’m at work browsing your blog from my new iphone 4! Just wanted to say I love reading through your blog and look forward to all your posts! Carry on the superb work!

  15. Gavin says:

    I am interested to what extent teachers use culture learning strategies. I am considering using a 5 point scale from “not at all”, “not often”, “sometimes”,”often” to “to a great extent”. Is this the right way to go in your opinion? I have also considered “never” and “always” as the extreme choices.

  16. Thanh says:

    Hi Palle,
    Disagree and agree survey would be bipolar, wouldn’t it? Since it is not a knowledge question, it is not wrong or right. If the person doesn’t know, it means neutral, still in the survey, exactly a 5 in 0-10 scale or 2.5 in a 1-5 scale.

    Hi Patrick,
    Just an idea. How about you have 6 questions, 1. Rate the audio quality (you can split this to 3, speaks too fast? too low? weird accent?), 2.Rate the picture quality, 3. Rate the content usefulness, 4. Rate the content attraction, 5. Rate the loading, 6. Put in order of importance to you, audio, picture, usefulness, attraction, loading.

    Hi Gavin
    “Not often” sounds the same as “sometimes” to me. Is “rarely” better?

  17. Thanh says:

    Hi Patrick,
    Complimentary to what I said. I still don’t know how my “method” can calculate the overall score, sorry. Why do you need it? You can look at each aspect to make improvement.

  18. Stephen Okeyo says:

    Great reading. Fortifies my understanding of how to make quantitative data from qualitative information

  19. Amazing layout I think.

  20. Wonderful work! That is the kind of info that should be shared across the web. Disgrace on the seek engines for not positioning this submit upper! Come on over and talk over with my web site . Thanks =)

    1. Hanna J says:

      Thanks for your support! We appreciate you :)

  21. Fran says:

    Is there a way to prompt for a comment by the participant if they score something low? Example: On a 4 point scale, they mark something “good” with excellent being the highest sciore. Could it prompt with a comment, such as… You gave the instructor a score of “good”. Can you tell us what he could do to improve his score to “excellent” next time?

    1. Hanna J says:

      Hi Fran – The best way to do that would probably be to use Skip Logic. So if your respondent marked 4, you would set your survey to skip them to a page with a question just for that response. For more information about skip logic and how to use it, check out this help center article: http://help.surveymonkey.com/app/answers/detail/a_id/39/~/the-principles-of-skip-logic-and-how-to-use-it.

  22. Benr says:

    Hi, I have been reading some research that uses a four point rating between 0-1 with the followiing intervals:
    lowest – 0
    second – 0.333333333
    third – 0.666666667
    Highest – 1

    I intend to use the same for my question ratings – do you think this is ok?

    Thanks

    1. Hanna J says:

      Hi Ben – We recommend that you use words when possible to label your rating scales. See this blog post for more information: https://www.surveymonkey.com/blog/2012/01/24/words-speak-louder-than-numbers/

      If you must use numbers, and need them to be on a 0 through 1 scale, can you use a 5-point scale and make them percentages? 0%, 25%, 50%, 75%, and 100% seem like much more intuitive responses to us than 0, .333333333, .666666667, and 1. What do you think?

  23. Adam says:

    I would argue that “Somewhat too long” and “A little too long” are equivalent responses in the minds of most users, thus the 7-point example given above could be reduced to 5 points. Adding responses to your scale that have no meaningful difference between them just dilutes your data.

    1. Hanna J says:

      Hi Adam – You’re right, you want to try and get the information you need through questions that are as succinctly as possible. Our research shows that many people differentiate significantly between “somewhat too long” and “a little too long,” but you always want to use your best judgment. Thanks for sharing your insight!

  24. Sylvie Potoniec says:

    I appreciate all the great information. I am using a 7 point scale with a Not Applicable choice. Will the results be accurate?

    1. Hanna J says:

      Hi Sylvie – We recommend using a 5-point scale if your what you’re measuring is unipolar and a 7-point scale if what you’re measuring is bipolar. It sounds like yours is a 6-point scale with a n/a option which we do not recommend. We use odd numbered (5 or 7) scales because it allows for a midpoint. We also do not recommend supplying a not applicable choice unless you are specifically interested in those who feel the question is not applicable as it may lead to people simply avoiding filling out your measure. A better way is to use skip logic so that those for whom the question does not apply never see it in the first place. Does that help? Let us know if you have any follow up questions. Thanks!

      1. Sylvie Potoniec says:

        Just to clarify, I am using a 7 point scale and measuring is bipolar. I will look into skip logic!

        Thank you!

  25. jackie a says:

    how do you identify the 1-10 scale with out qualifing the high and low ie…
    “How would you rate the meal on a scale of 1-10, 10 BEING THE BEST?”
    In this example the phrase “10 BEING THE BEST” should be able to be replaced by one word that describes your scale. Alternatively there should be a different word that describes a scale where #1 is the best. The end question would be phrased,
    “How would you rate your meal on a ______ scale of 1-10?

    1. Kayte K says:

      Hi Jackie, we recommend keeping your scales to 7 points instead of 10. Hope that helps!

  26. Isha says:

    I am not clear about polar scales (negative/positives) and polar scales (non neg/pos). Please suggest.

    1. Kayte K says:

      Hi Isha- we’d be happy to help! If you could kindly send a note to support@surveymonkey.com, they can help you get started in the right direction.

  27. Anthony says:

    what are some of the academic articles about this for those of us who want to dig deeper?

    1. kaytek says:

      Hi Anthony, here’s an abstract that you can start with! http://psycnet.apa.org/journals/apl/60/1/10/

  28. Steve says:

    Can anyone point me to the academic scholarship that demonstrates the improved effectiveness of 5 and 7-point scales? I’m being asked to change our existing 5-point scale to a 10-point scale, and if I’m going to push back at all, I need some hard facts.

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