I'm getting multiple inconsistent answers from the same contacts

The most common reason for getting lots of inconsistent answers from the same contacts answering your surveys is that respondees can answer the survey multiple times. This can of course be useful in many cases, but in some cases it can skew the survey results.

To combat this, you can set the survey to allow only one response per respondee. To do this, start by navigating to Surveys in the navigation bar. Next, select the survey you want to edit. 

Once you're in the survey editor, navigate to Settings tab at the top. Then scroll down to "Allow the respondee to edit their answer with the same device", and uncheck the option if not yet unchecked. Now the survey only accepts one answer from a device.