The Sizmek MDX platform identifies browsers using a third-party cookie written by the Sizmek MDX platform ad serving system. These unique cookies represent the beginning point for the reported unique impressions (adjusted) and average frequency metrics.

When a browser makes an ad request, the Sizmek MDX platform determines if a cookie is present:

  • If there is no cookie, the platform writes a cookie to the browser and records the transaction without a cookie value (i.e., it is recorded as a non-cookie impression). 
  • If the cookie already exists, Sizmek resets the cookie expiration date to be 90 days from the current date.

Users can elect to block or refuse cookies, in which case they will not be identifiable for purposes of reporting unique cookies. Additionally, users can periodically delete their cookies. They are issued a new cookie (with a new and different value than their previous cookie), and their activity during the subsequent visit is attributed to a new and unique cookie.

To address situations such as these, Sizmek identifies persistent cookies relevant to the reporting tool based on the following:

  • reported advertiser/campaign/creative
  • start date of the reporting period (days (relevant only for Predefined reports), week, month, campaign lifetime)
  • cookie creation date

Only cookies that are both (a) recorded as having been served the reported advertiser/ campaign/creative, and (b) created prior to the beginning of the reporting period are used to compute the unique impressions (adjusted) and average frequency metrics. These parameters, therefore, exclude any cookies where the browser was either exposed to any Sizmek MDX platform-served campaign for the first time after the start date of the requested report, or had deleted or blocked cookies and therefore may have been exposed to the same advertiser/campaign/creative using multiple cookies, which could potentially inflate the unique impressions metric.

Once these qualified cookies are identified for the specific report, the Sizmek MDX platform computes an average frequency for those cookies by dividing total cookied impressions in this subset of total impressions for the report by the qualified cookies for the report. To project total unique impressions (adjusted), the Sizmek MDX platform then applies that average frequency figure computed for the specific report, to total reportable impressions (after filtering as described above). These processes are computed separately for each report period (week, month, campaign lifetime) such that the unique cookies and average frequency are specific to the report.

Note: The adjusted unique numbers, which are highlighted in the report in red, indicate that the number of qualified cookies on which the unique calculation is based is under the threshold of 313.

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