Rating Scales - Number of Points on the Scale and Accuracy of Feedback

Question

Context: Collecting user feedback on locations they visit.

I wondered whether anybody has any experience or knows of research on the 'length of scale'.

The options are:

1 - 2 Point Scale ( Good / Bad )

2 - 3 Point Scale ( Good / Neutral / Bad - or 1 to 3 rating )

3 - 5 Point Scale ( 1 to 5 rating )

The issues relate to:

A - Completion Rate - ie whether they respond to the scale

B - Accuracy - whether how they respond is an accurate gauge of their feeling (ie do users avoid using the extreme ends of the longer 1-5 scale?)

I've found this existing question and response which is similar. However my interest is for the use within an app rather than the 'use in user research' scenario.

Is there a function to get the optimal number of choices in a Likert scale?

https://achilleaskostoulas.com/2013/09/09/four-things-you-probably-didnt-know-about-likert-scales/

Answer 1

There's no function of which I'm aware to find the optimum number of choices for a Likert-type scale. Individual differences would get in the way of any such function: what's optimal for me is not necessarily optimal for you.

The findings of Miller et al. on short-term memory limits, plus practical experience, suggests that 9 or 10 boxes is about the upper limit of usefulness. Larger than that introduces difficulty in holding enough in short-term memory to discriminate accurately.

My personal experience is that 7 is the practical limit, or 6 if you want to force a choice. If you're satisfied with coarser granularity, use 5 or 4. And of course if it's not a situation where nuance is possible, then there's no sense using more than 2 or 3.

Many Likert-type scales label the intermediate points. I prefer not to, because that can cause useless mental debate about which intermediate box the respondent should check.

Whether people will treat the scale seriously is also an individual-differences issue. If it's something that interests them, and if you tell them up front that you'll provide feedback (most people like to know where they stand with respect to others), they're more likely to respond than if it's a black box with nothing in it for them.