How and why marketing vendors (Facebook, Google, etc...) use an attribution window
Attribution Windows Explained
Most marketing vendors have the concept of an "attribution window". This concept refers to the way that vendors take credit for orders even if a customer did not click through an advertisement on their site directly before they made a purchase (what we would call the "last click" vendor). Most vendors have different attribution window choices along with a default option. As an example, Facebook allows you to choose between 1 and 7 day view and click windows with a default of 1 day view / 7 day click. Google's default window is a 30 day click window. What does this mean? Take a look at this customer journey:
This customer came to your site on January 1st after clicking through a Facebook ad. They did not buy on that initial visit. They came back 2 days later after clicking through a Google ad, but again did not purchase. Finally, 2 days later they typed in your URL directly and made a purchase.
At the default settings, both Facebook and Google are going to count this as an order or conversion that can be attributed to their ads. For Facebook, this individual clicked through an ad, and then purchased within the next 7 days. For Google the purchase was also within the 30 day window.
However, if you have changed your settings to a 1 day click / 1 day view window for Facebook, then Facebook would NOT count this order as a Facebook "conversion".
So what attribution window is correct? It depends on your business. Do you have a quick customer journey cycle that lasts only a few days? Or does the customer journey take a week or longer? For lower priced items you will typically find that a shorter window (1 day click / 1 day view) gives you the most accurate results.
In the example above, it's likely that seeing and clicking on an ad in Facebook likely did contribute to this customer making a purchase. It was their first interaction with your brand. But how much did Google contribute? And what if the Facebook click came after they visited your site through 3 other vendors? Setting your attribution window comes down to product type, price points, and other factors that require a real understanding of the path customers take to finding and purchasing your products.