Many years ago, search engine results were pretty much static. For a specific query, the SERPs were almost the same for every user. Going forward, search engines became more sophisticated and now the results for a specific query vary, taking many factors in to considerations.
One of these factors is the location from which the user is making the query: two people in two different places might receive different search results for the same query. Other factors taken in to consideration by the search engines include what the user searched before and what the user actually clicked before. Nowadays, the SERPs are very different and are personalized based on the user.
The goal of a rank tracking tools is to make one or more queries to the search engine and report on the position of the website being monitored. The position, however, is what the search engine decides to show to the software, and is not necessarily will see. All rank tracking tools present artificial results, in the sense that they are not what the user actually sees.
The concept of “position” as we knew it has become completely outdated thanks to the personalization of the SERPs. For this reason, SEOs started using the concept of “average position”. This is an average of all the various positions a website occupies, as seen by different users. But Only the search engines can accurately measure average position.
Webmasters can use a Google tool called “Search Analytics” to see the average positions of a website for specific queries. Even if Search Analytics data is not complete, the average positions provided should be considered the more accurate representation of what users actually saw in the SERPs.