A "Slider" question is a great way to measure the intensity of respondents' attitudes, opinions, or satisfaction. In our reports, besides the average of the collected ratings, we also present the deviation.
The deviation allows you to easily assess how much the general sentiment of the respondents deviates from the completely neutral value (the middle of the scale) towards an extremely positive or negative one.
This mechanism is always the same, regardless of the slider's length. To illustrate this, let's trace it using two of the most popular examples: a 5-point scale and an 11-point scale.
Example 1: 5-point scale (from 1 to 5)
Let's assume we ask users for a rating on a standard scale from 1 to 5. How will the system calculate the deviation from their answers?
Step 1: Calculating the average of the responses
The system first sums all the answers given on the slider and calculates their average. Let's assume the calculated average from the votes is 3.5625.
Step 2: Determining the middle of the scale
We look for the exact middle (the neutral point). On a scale from 1 to 5, the middle is, of course, the number 3.
Step 3: Calculating the shift from the middle
We check how far our average is from the designated middle: 3.5625 - 3 = 0.5625 Tip: The result is positive, so we know that the average of the answers is shifted to the right side of the scale.
Step 4: Presenting the deviation in percentages
We check how many "units" separate the middle from the extreme ends of the scale (1 --- 2 --- (3) --- 4 --- 5). From the middle (3) to the extremes (1 or 5), we have exactly 2 parts. This is our maximum possible deviation.
To get the final result, we divide our shift by the maximum deviation and convert it to percentages: 0.5625 / 2 = 0.28125 0.28125 x 100% = 28.125% (approximately 28.13%)
Conclusion: The respondents' answers on this scale deviate by 28.13% from the middle to the right side.
Example 2: 11-point scale (from 0 to 10)
Now let's see how the same mechanism works for the very popular 0 to 10 scale, known for example from NPS (Net Promoter Score) surveys.
Step 1: Calculating the average of the responses
The system collects the votes. Let's assume this time the average rating given by respondents is 8.24.
Step 2: Determining the middle of the scale
For a scale starting from zero (0, 1, 2... 8, 9, 10), the middle and neutral value is 5.
Step 3: Calculating the shift from the middle
We subtract the middle from our average: 8.24 - 5 = 3.24
Step 4: Presenting the deviation in percentages
Again, we check the distance from the middle to the extremes (0 --- ... --- (5) --- ... --- 10). From the middle (5) to the extreme values (0 or 10) we have exactly 5 units to cover.
We divide the calculated shift by the maximum deviation and convert it to percentages: 3.24 / 5 = 0.648 0.648 x 100% = 64.8%
Conclusion: The respondents' answers on this scale deviate by 64.8% from the middle to the right side.
Good to remember: In both of the above examples, the deviation was right-sided (the result from Step 3 was positive). If the collected ratings were very low, and subtracting the middle of the scale from them resulted in a negative number, it would mean a deviation to the left side of the slider. However, all the math remains exactly the same!