How ClickBank’s “Gravity” Is Calculated
Have you ever wondered exactly how ClickBank calculates the "gravity" number it displays for each item in the marketplace? The ClickBank website explains that gravity is the:
"number of distinct affiliates who earned a commission by referring a paying customer to the publisher's products. This is a weighted sum and not an actual total. For each affiliate paid in the last 8 weeks we add an amount between 0.1 and 1.0 to the total. The more recent the last referral, the higher the value added."
The fastest way to kill your reputation as an affiliate is to recommend products that sound great on the sales page, but don't deliver. How can you tell which products to avoid? Refund rates. Instant Affiliate Accelerator estimates refund rates on thousands of ClickBank products daily. Check before you promote!
Okay, that gives you a vague idea. Let me explain exactly how it's calculated.
When an affiliate makes their first sale of a product, ClickBank adds 1.0 to the gravity score for that product. If they make another sale (or any number of additional sales) on the next day, ClickBank continues to add 1.0 to the gravity for that affiliate. If on the other hand, that affiliate doesn't make another sale on the next day, ClickBank adds only 0.96 to the gravity for the product for that affiliate.
If yet another day later, that affiliate has still not made another sale of that product, that affiliate's contribution to that product's gravity is reduced to 0.9216. The next day, it is reduced to 0.88474. If you do the math, you'll see that every day that an affiliate doesn't make another sale, their gravity contribution is multiplied by 0.96. This continues for 8 weeks, after which that affiliate's sales are dropped from the gravity calculation for that product.
So exactly how one should go after a product. Clickbank does not show total number of sales made for a product neitherr it shows how big the market is for that particular product. I am trying to select a product to promote now but as yet am undecided...If an affiliate sale is refunded, that sale is deleted from the calculation (though if the affiliate has made other sales of the product, they will continue to contribute to the product's gravity).
An individual affiliate can never add more than 1 point to a product's gravity, no matter how many sales they make, and no matter how many days in a row they have sales. Because of this, gravity does not directly tell you how well a product is selling -- if one affiliate is referring 1000 sales a day, the gravity score will still be 1.0. The volume of sales will however affect how high in a category the product ranks.
While I'm on the topic of ClickBank's rankings, here are a few other things my experience suggests affect how high a product ranks. There are the obvious things: sales volume, gravity, and average commissions per sale.
Interestingly, I'm pretty sure the seller's price limit affects their ranking also, because the day after I got a price limit increase for CaRP, I jumped up in the rankings even though I didn't get any sales on that day.
September 5th, 2008 at 5:15 pm
[...] found Antone Roundy’s assumptions about calculation of the gravity to seem really correct. So, here are basic points of his [...]
August 26th, 2009 at 9:38 pm
Finally a well-detailed explantion. While I'm a little tired to begin calculating exact numbers in my head and their actual implications, this gives me a much better feel as to what it means. Thanks!
September 12th, 2009 at 3:28 pm
So exactly how one should go after a product. Clickbank does not show total number of sales made for a product neitherr it shows how big the market is for that particular product. I am trying to select a product to promote now but as yet am undecided on the various factors to determine a product to pick up.