Why do I see a user assigned to more than one Variation Group within the same Campaign?

In rare circumstances, you may notice that a user (as defined by a single SiteSpect GUID) has been assigned to more than one Variation Group within the same Campaign. This happens normally for less than 1% of users assigned to a Campaign and can happen in an isolated set of cases like the following examples, whose basis is multiple concurrent requests to start a new visit to SiteSpect or unsynchronized cookies:

  • The user is on a search engine results page and opens multiple links to a SiteSpect Site in multiple tabs.
  • The user's browser closed or crashed while the user had multiple tabs open to a SiteSpect Site. Upon starting a new visit after 30 minutes, the user chooses to restore all tabs.
  • The user has a bookmark folder with multiple links to a SiteSpect Site and uses the Open all Bookmarks option to start a new visit. SiteSpect opens in multiple tabs.
  • The user periodically uses a cookie sync between devices and browsers. If the sync doesn't happen often enough, the user might go through assignment logic for each device and end up with different assignments (which are overwritten after the next sync). Multiple devices.
  • A program that replays a visit using a fixed set of SiteSpect cookies in which the user has passed the robot test.

The problem occurs when a user has multiple versions of an SSID cookie, due to either rapid or concurrent requests from multiple tabs or un-synced cookies. Multiple versions of this cookie can confuse SiteSpect as to the state of the user. In such cases, SiteSpect may assign a user to more than one Variation Group in an A/B test.

If the user refreshes all tabs open to SiteSpect, each instance is assigned to the same Variation Group as the last tab to be assigned.