Discrepancy in the number of sessions in different collection methods

When using the OWOX BI sessionization algorithm in OWOX BI Pipeline: Google Analytics to Google BigQuery, you may notice a larger number of sessions as compared to the Google Analytics statistics. There can also be differences in how particular sessions are defined.  

Why are there more sessions in OWOX BI tables than in Google Analytics?

No filters

One of the main advantages of the OWOX BI sessionization algorithm is that it allows you to collect the most complete data from your website. OWOX BI doesn't filter the incoming data so that you can always have a full view of all your hits. If you don't want to see certain values in your particular report, you can filter them out when processing the data.

Hits that weren't collected by Google Analytics

Due to technical reasons, such as delays in sending hits from the website, OWOX BI Pipeline hit data tables can have more hits than Google Analytics. If these extra hits start a new session, this will result in an additional number of sessions in the OWOX BI session data tables.

The Last Click attribution model, if different from the model used in Google Analytics.

By default, Google Analytics attributes sessions to traffic sources using the Last Non-Direct Click attribution model. The current version of the new OWOX BI sessionization algorithm uses the Last Click attribution model. In some cases, the difference between attribution models can influence how a new session is defined.


For example:


Google Analytics attribution model
(Last Non-Direct click)

OWOX BI attribution model
(Last Click)

November 1st, 12:00 — a user visits the website via a Google pay-per-click campaign



November 2nd, 16:00 — the user visits the website again by typing in the URL directly



November 2nd, 16:15 — the user visits the website once again by clicking a Google pay-per-click display ad




As you can see, in the third event, Google Analytics doesn't display a different source and doesn't start a new session because 30 minutes (the timeout period) haven't passed.

In OWOX BI, the google/cpc source differs from the previous visit (direct) and the new session will start.

As a result, Google Analytics shows 2 sessions while OWOX BI shows 3. If this happens often, you may see significantly more sessions in OWOX BI than in the Google Analytics statistics.

Different timeout periods

A session timeout is a period of inactivity after which the current session ends and a new session begins. By default, the timeout period is set to 30 minutes in both Google Analytics and OWOX BI. If session timeout periods are set to different amounts of time in OWOX BI and Google Analytics, the number of sessions will differ between the two services.

Tracking via Measurement Protocol

If an event is sent via Measurement Protocol after more than 4 hours after taking place, this may lead to Google Analytics not processing this hit. However, it will appear in OWOX BI tables and start a new session. This may result in a bigger number of sessions in OWOX BI.


Why may session start and end times differ?

OWOX BI sorts hits by two time values:

  • Server time (the time when the hit was collected at the OWOX BI access point) — the “time” field in OWOX BI tables.
  • Client time (the time when the hit was sent is defined by the time settings on the user's device and may differ from the actual time) — the timestamp in the Session ID parameter.

The sorting is performed twice - first by the server time, and then, each minute, by client time, in order to take account of the possible delays in sending hits. Double sorting provides for higher accuracy than sorting only by the time the hit was received by the server.

Why may campaign names and keywords for AdWords-generated visits differ between Google AdWords and Google Analytics?

When sessions are computed using the Google Analytics sessionization algorithm, the traffic source data is obtained via the GA Core API. With the OWOX BI sessionization algorithm, sessions are computed considering the raw data collected in Google BigQuery via the AdWords API.

The data about the same visit may differ between AdWords and Google Analytics. Independence from Google Analytics makes it possible to avoid data sampling and get the complete data about traffic sources for AdWords campaigns with auto-tagging. OWOX BI session data tables always provide relevant data, since AdWords reports are a primary data source for OWOX BI Pipeline.

We always strive to provide you with the data you can rely on. If you still have any questions or concerns regarding data discrepancies, please feel free to contact us at bi@owox.com.

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