Siteimprove Analytics appears to be confident enough about their cookieless tracking technology (compared to cookie based tracking) to claim:
In general, Visitor Hash is expected to be more persistent, resulting in a drop in the number of unique visitors. Since cookies are known to have an increasingly short lifetime, leading to overestimated data about unique visitors, we consider the Visitor Hash technology to be more accurate at capturing information about unique and returning visitors
When Cookieless tracking is enabled, it replaces the traditional use of cookies with a "Visitor Hash" made of non-personal information only. This information includes hashed IP and HTTP header values including browser type, browser version, browser language, and the user agent string. The Visitor Hash only consists of server-side attributes passed along by the website server.
Note: Siteimprove analytics does not collect client-side attributes. The Visitor Hash is used for the same functionality as the cookie and nothing else. For some websites, like intranets, there is an increased likelihood that the visitors could end up getting the same Visitor Hash as they might all be accessing the site from the same IP and on the same device setups. In those cases all page views would appear to be coming from one, or a few, visits. That's why we recommend excluding those domains from using cookieless tracking. See the "How to exclude domains from having cookieless tracking enabled" section below for more information.
In general, Visitor Hash is expected to be more persistent, resulting in a drop in the number of unique visitors. Since cookies are known to have an increasingly short lifetime, leading to overestimated data about unique visitors, we consider the Visitor Hash technology to be more accurate at capturing information about unique and returning visitors
When Cookieless tracking is enabled, it replaces the traditional use of cookies with a "Visitor Hash" made of non-personal information only. This information includes hashed IP and HTTP header values including browser type, browser version, browser language, and the user agent string. The Visitor Hash only consists of server-side attributes passed along by the website server.
Note: Siteimprove analytics does not collect client-side attributes. The Visitor Hash is used for the same functionality as the cookie and nothing else. For some websites, like intranets, there is an increased likelihood that the visitors could end up getting the same Visitor Hash as they might all be accessing the site from the same IP and on the same device setups. In those cases all page views would appear to be coming from one, or a few, visits. That's why we recommend excluding those domains from using cookieless tracking. See the "How to exclude domains from having cookieless tracking enabled" section below for more information.