In short Facebook & Google Analytics use different attribution models.
Provided you have the Facebook tracking pixel installed on your pages and you are pushing in a conversion(s) as an event:
Facebook will take credit for a conversion if the conversion happens with 28 days of clicking a Facebook ad or 1 days within viewing a Facebook ad i.e. the ad appeared in your Facebook feed.
How many times have we seen a remarketing ad on Facebook that reminds us to buy something we looked at earlier? Quite a lot in my experience and none of this is captured by Google Analytics.
Using the default attribution model, Google Analytics will give full credit to the last channel clicked before the conversion, unless that channel is Direct in which case it will attribute the conversion to the last channel before (if known), looking back 6 months.
So which report is correct?
Neither. They both look at results from different views. Google Analytics will not give any credit to a Facebook ad that was merely viewed and will not give any credit to a Facebook ad that was clicked and did not result in a conversion within that session.
In practice, you have to look at both sets of data with a clear understanding of how different platforms report and attribute conversions.
Ok, but which should I show the client? If the client has a clear understanding of attribution models and is not likely to get tied up in knots, trying to get to the correct attribution model, you can show both reports. In my experience, I have not met many clients who do not get confused trying to understand attribution!
More likely you have to look at attribution across many models and data from multiple platforms before making conclusions about the performance of a channel. As an analyst, this is your job:
How much did each channel contribute to the company’s bottom line and how should we optimise our marketing focus going forward?
If you’re trying to answer the above question using only Google Analytics reports (based on the default attribution model), then you are only seeing a fraction of the whole picture and are almost certainly not giving advice and insight that maximises results from marketing activity.
Working in an agency you will also see a tendency for different teams to use different reports i.e. the social team will mainly look at and rely on Facebook Analytics and the paid team will mainly look at and rely on Adwords reports, each of which will report very different results than Google Analytics which is measuring multiple channels and attributing value to a channel based on it’s attribution model.
In reality, Google Analytics is still the best tool we have thats free since it measures across channels; Facebook & Adwords reports etc only measure their own siloed channel and report everything from this (unrealistic) view. Google Analytics is more realistic since multiple channels are usually always involved but it is still far from adequate.
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