Discrepancies between Zemanta's reporting and your analytics provider can happen. Before any sort of panic sets in, don't worry - this is normal for programmatic advertising.
Why does this happen?
In short, because of the different reporting methodologies between individual networks and your analytics solution. In our experience, you can expect to see a 10-30% click discrepancy across desktop and mobile web placements.
Let's take a look at some reasons why click discrepancies happen:
Analytics Implementation: A very common reason for click discrepancies is that your analytics solution might not be properly running on all article pages across the site, especially on brand new sections (such as landing pages) that you've created specifically for content promotion with Zemanta campaigns.
Partial Page Load: Once online users click on your ad they are directed to your content wherever it is hosted. Sometimes visitors might click on the ad but navigate away before the page fully loads.
Browser Preferences: Some visitors may have their browser privacy preferences set to disable cookies, images, or JavaScript. Since many popular analytics solutions such as Google Analytics operate with JavaScript, the user's session cannot be recorded, but a click is still registered in Zemanta with the network. For example: An online user has the Firefox Enhanced Tracking protection enabled.
Sessions vs. Clicks: There is a difference between clicks that Zemanta records from networks and the visits or sessions recorded by your analytics solution. Zemanta records a click anytime a user clicks on an ad, while Google Analytics records a single Session/Visit for all user interactions within a given time frame (which expires after 30 minutes of inactivity). For example: If an online user reaches the landing page through Zemanta twice within the 30 minutes time frame, Google Analytics will only record it as one Session/Visit.
Sampling: Many free analytics solutions (namely Google Analytics) are based on a sampling of all visits to your site rather than giving you access to all of the raw data.
What should you know beforehand?
Zemanta helps you navigate the ever-changing nature of programmatic advertising by providing complete transparency into the clicks, CPCs, impressions, and more, helping to understand where the discrepancies are and how to limit them.
Clicks and Sessions are different metrics: Zemanta tracks Clicks, while Google Analytics tracks Sessions. If an online user clicks twice on the Zemanta ad within the 30 minutes timespan without closing the browser, Google Analytics records this action as one session.
Your site has a server-side URL rewrite: A small percentage of websites do not allow arbitrary parameters in the URL and consequently serve error pages when you include those parameters. We suggest that you lobby your webmaster to allow arbitrary URL parameters.
Your landing page might redirect to a different page: Redirects in landing pages can often keep the Analytics code from loading and properly identifying the paid traffic. For example: If your ad leads to http://www.mydomain.com/index.html, but you've created a 301, 302, or JavaScript redirect from that URL to http://www.mydomain.com/page2.html, the campaign information that was originally appended to the landing page is lost upon redirection.
Bookmarked websites and Session timeouts: Users may click on the Zemanta ad, bookmark the site, and come back later during a different session. In Google Analytics, this would be counted as 2 separate sessions while Zemanta will only count this as one click.
What can you do to eliminate click discrepancies?
We have some useful tips and recommendations.
Implement Google Analytics code correctly: Add the Google Analytics code to the header of each page, including home pages, section fronts, and mobile pages. Implementing the code too far down on your web page will result in missed clicks if the page isn’t fully loaded. Also, make sure the analytics code loads first.
Keep your Google Analytics code up-to-date: Check if the latest GA script code from Google is in use. Make sure you add the UA and Domain attribute as described on that page.
Optimize for mobile: Keep loading times in mind. If it takes a mobile site more than 4 seconds to load, expect over a 25 % dropoff from click to pageview.
Analyze your landing page performance: Delays in page load time can lead to discrepancies. You can use Google Page Speed Insights to get suggestions for website optimizations.
Implement UTM tags on the campaign level: When implementing UTM tags on your Zemanta campaign, add them on the campaign level, rather than the URL. Dynamic parameters are not supported by the URL level.
Avoid multiple redirects: If you are directing visitors to HTTPS pages, make sure all your URLs in Zemanta are pointing to HTTPS instead of HTTP. This will help you avoid additional redirects.
Additional measures
Add the Zemanta Pixel to your landing pages and compare clicks with your analytics solution.
Block publishers and shift budgets away from networks that have larger discrepancies between clicks and Zemanta Pixel tracking.