How to Convert one Rating Scale to Another Measurement Scale

If your organization is committed to staying on top of the latest trends in tracking performance, then you're most likely going to come across an unexpected decision; which rating scale to use.
This isn't usually a problem when you're starting a tracking process -- but what about those of us who have chosen a scale and for a variety of reasons are considering changing it!  What then?

What Options Do You Have?
  • Start Fresh. You can always draw a line in the sand and start fresh.  Be sure to communicate to your management teams and everyone involved in the process that you will be starting fresh.  One thing you can expect is your scores or ratings to either go up or down drastically, so you will have to prepare everyone involved in the process that you are setting a NEW BENCHMARK and that your ratings haven't shifted up or down - they are what they are with this new result.
  • Run Parallel. If your organization cannot afford to start fresh, you might consider running parallel surveys and gathering two sets of data as you make the transition from the old rating scale to the new rating scale.  After you've gathered enough data, you can compare the two scales and see what impact this has on your metrics.
  • Interpolate. Yet another option is to run a test survey with your customers asking them to answer the same question using two different rating scales.  This will give you the ability (over time) to predict where the old rating would fall in the new scale.
Why Switch At All?

There are advantages and disadvantages no matter which measurement scale you choose.  Not only that, but there are academic camps at each end of the spectrum and in between.  In other words, you have to choose the scale that matches your objectives.
Say that you started doing the Net Promoter Score in your organization using the "Excellent, Very Good, Good, Fair and Poor" rating.  And now, you want to go more traditional and use a 10 point scale.  What's more important to your organization?  Is it having the trend data or is it "matching up" to what Reicheld recommended in his book; The Ultimate Question?  If it's more important to you to match up and benchmark your organization, then the pain involved in transitioning might be worth it.  If your organization is large and your customers might be confused, then the transition might do you more harm than good.

Don't Switch Without Doing The Following:
  • Communicate.  This can never be emphasized enough.  Be sure to communicate inside your organization early and often.  Make sure that everyone in the organization understands that there will be changes in the ratings and fluctuations -- simply because you are changing scales.  This is normal and to be expected.
  • Pick a time that is uneventful. Switching your rating scales after you've installed a new computer system isn't a good idea.  You want to pick a span in time when it's about as stable and uneventful as is standard in your organization.  You will already see shifts in scores and ratings - you don't want to mix in REAL shifts due to an actual change in practices.
  • Be Patient.  Measuring customer satisfaction or organizational performance are emotional issues -- especially if you have people whose compensation is based on the results of these surveys.  Please be patient with the transition and focus on performance and service instead of the survey.
Switching from one scale to another isn't as cut and dry as you might think.  As soon as you get into the details and the results, you'll soon realize that it's a bigger decision that requires a little extra thought.  But don't let that deter you from making a change that will ultimately benefit your organization and your customers.
Stay current with what's happening in the world of feedback and measuring satisfaction.  Go ahead and investigate best practices and benchmarking surveys that have been tested by the best organizations in the world; like Net Promoter Score for customer satisfaction and Gallup Q12 for customer satisfaction.  Don't kill yourself reinventing the wheel and don't be afraid of making a change.