Analytics packages, such as Google Analytics, measure different metrics than ad servers, so their reports don’t reconcile with DFP. Here are a few reasons for disparities between Google Analytics and DFP:
Page views versus impressions
Analytics tracking is based on page views. In contrast, DFP ad server concepts are, by design, not page-specific:
- An ad tag can be placed on multiple pages.
- An ad unit can be associated with many pages.
- A line item can be targeted to multiple ad units.
- A line item can serve to a single page multiple times.
DFP counts impressions delivered to ad tags; analytics packages count the execution of analytics tracking code. Since these snippets of code are located in different parts of your page code, both scripts might not load or execute on every page view.
Since there is no interaction between ad tag code and analytics tracking code, analytics packages cannot account for unfilled impressions, which can be caused by any number of variables:
- A lack of inventory
- Firewalls and misconfigured security software
- Ad blockers
- Intermittent network connections
- General latency
Some publishers serve DFP tags in iframes. Browsers that don’t support the
<iframe> tag don’t report an impression, but an analytics package does count this as a page view. Ad tags within an iframe can result in an extra round trip between the browser and server. This additional latency can cause some users to leave the page before the browser has enough time to make the calls to both the analytics package and DFP. If the analytics tracking code is present within both an iframe as well as the parent frame, the analytics software registers an inflated number of page views.
Comparing referrer URLs to DFP clicks is not advised. Referrers in analytics are not an accurate measure of clicks or landings for the following reasons:
- Referrers can be disabled by users.
- Internet security applications can block referrer data.
- Firewalls and proxy servers can filter referrers.
- Users can spoof referrers to prevent servers from knowing where they’ve been.
- Internet Explorer does not send referrer data when switching from either: (a) HTTP to HTTPS, or (b) any non-HTTP/HTTPS protocol (e.g.,
file://) to HTTP/HTTPS.