Products
Webtrends Visitor Data Mart
Issue
Resolution
Additionally, differences in session tracking may allow a hit to be tracked in Analytics, but not show up in VDM.
Analytics also utilizes smart trimming, whereas VDM does not. VDM also has very particular event retention settings that may remove data that is still visible in Analytics as well.
Analytics has fallback sessionization (thirdparty cookie -> first party cookie -> IP/user agent), VDM does not. It?s third party cookie -> first party cookie,only. There is no capacity for IP/user agent. As a result, VDM will differ from Analytics in the visits and/or visitors by at least the rate identified in Analytics cookie rejection rate reports (with Analytics being higher).
Analytics de-dupes based on WT.tx_i for only afew days. For example, if a WT.tx_i value comes in on one day, and the same ID comes back two weeks later, Analytics counts it as a new record. In VDM, all invoice IDs are preserved for all time. Once a particular WT.tx_i is loaded,all server calls that include this value in the future are thrown out for all time. As a result, VDM will differ from Analytics in that these?duplicate? invoices are being thrown out, and Analytics may be including them(with Analytics numbers being higher due to the over counts).
Analytics breaks sessions over a time period boundary (midnight), VDM does not. As long as continued activity is still coming in, VDM will keep the session open forever. Result is that for traffic covering a date boundary, Analytics will see multiple sessions when VDM does not. So VDM will differ from Analytics in having better tracking of these sessions (with Analytics numbers being higher due to overcounts).
Caution must be taken in configuration of the profiles. ?Global? Analytics hit filters do not apply to VDM, and there is no facility in VDM for a visit filter of any kind.
In general, since these are two separate products, with different storage and aggregation methods, it is unlikely that the numbers will match across the two platforms unless you are very careful with the configurations.