When looking at the Product Tracker's graph results you will see orange bars and a blue area on it, let's explain what those mean:
- The blue area graphic represents the seller's inventory.
- The orange bars represent Units sold and there are two types of data you can see there. When the graph key to the left shows a dark orange it represents the actual number of items the seller sold, based on information given to us through Amazon's API (application programming interface).
- When the key on the results shows a light orange, this represents an estimate of that day's sales, based on rank; and while it will say Units Sold in the pop-up, if you see 'est' before the number of units sold, you'll know that that number is an estimate.
With respect to the inventory bars, there are the four reasons you tend to see light orange bar estimates over dark orange bar data for the ASIN.
Reason #1: Amazon takes a look at a BuyBox seller's inventory and gives that data back to JS through an API (Application Program Interface). Sometimes the data is correct, and sometimes it's not. JS will give you an estimate when we didn't like the look of the information Amazon gave us. For example, maybe one day the product's sales are given as 13, and the next they're reported as 975. In this case, we estimate off of the Best Seller Rank, instead of the change in inventory for the buy box seller....since the drastic increase in sales doesn't make sense.
Reason #2: The buy box seller has changed. Since we are tracking an individual ASIN, and the current seller who owns the buy box, when the buy box seller changes we show you an estimate. We do this until we can get two consecutive days to track the difference in inventory levels. If the buy box seller continues to change, we will continue to estimate the sales.
Reason #3: The seller's inventory is greater than 999, so we can't determine changes in their inventory level. So, we estimate sales from the Best Seller Rank.
Reason #4: The inventory increases instead of decreases, so we estimate from the Best Seller Rank. Sometimes sellers have returned items, sometimes they restock, and sometimes Amazon moves inventory around, showing a false increase in inventory. Instead of displaying the increases, we estimate off of the BSR to give you the estimates for this ASIN and the sales for that day.