When you're using Polar Analytics to track eCommerce sales data from either Shopify or Amazon, it's important to keep in mind that Polar has a few distinctions in how we approach order adjustment calculations.
Polar and Shopify Notes:
Order adjustments (such as item exchanges) can sometimes cause discrepancies in Shopify Analytics as these orders are counted twice: the day the order was processed and the day the order was edited. Returns are still calculated at the time they are processed like on Shopify Analytics. Polar Analytics pulls the original order data directly from the API, which makes the data 100% accurate.
Polar and Amazon Seller Notes:
On Amazon, orders can change their Fulfillment Status from Pending to Canceled. This implies that a past order could be taken into account one day, and disappear the next day in Amazon's reports. This could occasionally cause very small discrepancies between Amazon Seller and Polar as the change will be reflected instantly in Amazon and will be visible with the next refresh in Polar.
With that said, when you're comparing the data between Polar and Amazon, we recommend applying the "Fulfillment Status" filter to only account for non-cancelled orders. This article provides more detail on that process.