We're frequently asked which scale to use for survey questions. While there isn't a one-size-fits-all approach, we are advocates of a 10 point numerical scale. The 10 point scale has a number of advantages, including:

1) Familiar to respondents

Giving (or receiving) a score out of 10 tends to be familiar to most customers/people – whether it be from tests at school, from the reviews of footballers in newspapers, or by thinking of it in terms of a percentage.

2) Allows more advanced analysis

Choosing a 10-point numerical scale allows us to perform more advanced analysis since it gives the scale interval data properties. This means that a one-point increase at any stage of the scale is equivalent, which cannot be assumed with verbal scales.

When using techniques such as correlation and regression this is an important advantage.

3) Ten points allow more choices and more discrimination

Respondents can feel constricted if there are too few response options – although this is primarily a problem when there are five or fewer choices.

More significant is the fact that satisfaction data tends to be negatively skewed (towards the upper end of the scale) – meaning that even with more than five choices the actual opportunity for discrimination is reduced. We recently exchanged views on this topic with Professor Johnson of the University of Michigan Business School

Our recommendations are based more on our experiences than any documented studies. But I've seen various articles that help directly or indirectly support 10 point scales. This is why, to me, it makes sense to have more than just 7 scale points.

Professor Johnson is involved with the American Customer Satisfaction Index (ACSI), which also uses a ten point numerical scale.

4) It works

In our extensive experience it works! We specialise in customer experience research and measurement and have conducted hundreds of customer satisfaction surveys using this scale. We believe that it is the most suitable scale for measuring customer satisfaction. The 10-point scale has a finer distinction, which makes it easier to track changes and detect differences.