Variables in surveys

So, we have an external customer survey done for some key assets.

The results are surprisingly good and surprisingly consistent.

Where would I find any kind of indicator for what is a good standard variable to use.  You know the bit that relates to inbuilt bias, approach to response etc.

I know it's not law but, you know, someone might know something...

The people who did the survey should know (and in fact have reported along with the results) the margin of error (if that’s what you mean), or are you asking about a comparator?