If you were Google how would you correlate a visitors actions with their satisfaction level?
Obviously the visitor clicks on a link in SERPS and then returns right back that would be negative...
Different types of visitors actions to analyze...
1. Stays on the website for more than let says 20 seconds with no scroll and returns to SERPS
2. Stays on the website for more than a couple second with scroll and returns to SERPS
3. Stays on the website, no scroll, leaves via a internal/external link
4. Stays on the website, no scroll, leaves via a internal/external link