Avoid double-counting report totals

A single impression or click event can be associated with multiple placements, key-values, targeting elements, or yield groups because of overlapping targeting or tagging. In these cases, impressions, clicks, revenue, and other metrics can appear multiple times in reports that contain the Placement, Key-values, Targeting, or Yield group dimensions.

To avoid duplication, don't sum the metric columns, or use another dimension. Since the metric columns cannot be summed accurately, a "Totals" row does not appear for reports that include these dimensions.

• Placement dimension
  Metrics can overlap when the same ad unit is included in multiple placements. Use the Ad unit dimension for a more accurate breakdown of delivery.
• Key-values dimension
  Metrics can overlap when an ad request contains multiple key-values. Use Data Transfer reports for a more accurate breakdown of key-value delivery.
• Targeting dimension
  Metrics can overlap because this dimension displays multiple targeting elements, such as browser and operating system, that can apply to a single event. Filter your report by one of these elements (for example, "Browser=") for a more accurate breakdown of delivery.
• Yield group dimension
  Metrics can overlap when the same yield partner and targeting exist for multiple yield groups. Use the Demand channel and Yield partner dimensions for a more accurate breakdown of delivery.
  Report metrics data for events before February 20, 2018 do not overlap. Before this date, impressions and revenue were attributed to only one of the eligible yield groups in reports.

Placement example

If a "Sports" placement and "Events" placement both include the "Baseball" ad unit, any impressions delivered to the "Baseball" ad unit can be attributed to both placements. If 100 impressions deliver to the "Baseball" ad unit, you will see "100" for both placement report rows. If you simply summed the values, you'd include impressions twice and think 200 impressions delivered, which is incorrect. Only 100 impressions delivered.

Key-values example

When a Google Publisher Tag contains multiple key-values, such as "color=blue" and "shape= circle", each unique key-value is displayed in its own report row. If the example tag shown below delivered 250 impressions, there will be 3 rows in your key-values report that represent those impressions. If you simply summed the values, you'd include impressions three times and think 750 impressions delivered, which is incorrect. Only 250 impressions delivered.

googletag.defineSlot("/123456/hobbies/painting", [728, 90], "div-gpt-ad-123456789-0")
  .addService(googletag.pubads())
  .setTargeting("color", "blue")
  .setTargeting("shape", ["circle","square"]);

Yield group example

If a "Dresses Inventory" yield group and "Suits Inventory" yield group both contain the "Fashion ads" exchange and target the "Wedding Magazine" ad unit, impressions delivered to that ad unit and filled by the "Fashion ads" exchange can be attributed to both yield groups and will be represented twice for the Yield group report dimension.

If 15,000 impression delivered, you’ll see "15,000" in each of the yield group report rows along with the attendant revenue, so you cannot simply sum the metric columns without including duplicate metric data.