Hello real reality pi,
Here are some salary searches that I conducted which you may find helpful:
Notice that I put the exact phrase I was searching for in double quotations and that the box labeled 'Search Job Titles Only' is checked. These tricks will help ensure that only salary data for jobs with "Private Investigator" or "Field Investigator" as the title will be returned.
You will also find a blue bar directly underneath the average salary number. When you move your mouse over the bar you can see the level of confidence in the salary estimate and how many data points Indeed has to reference in order to make the estimate.
Obviously titles which have been posted on Indeed thousands of times will have a much higher level of confidence on salary estimates. As more PI and FI jobs in the Yonkers area are posted on Indeed, our salary estimate will have more data points to reference and have a higher level of confidence as well!
I hope this has helped you interpret the data you were seeing!