What is ClickBank Gravity?
Clickbank Gravity is a measure of how popular product is with affiliates. Although it can somewhat correlate with product sales, there is no direct connection. There can be products with zero-gravity that sell by the tousands and there can be products with much higher gravity that currently don't make any sales at all. Lets take a close look at how is clickbank gravity calculated...
Clickbank gravity formula
Clickbank gravity is a number that is calculated based on the number of affiliates that have made a product sale recently. Here's how it works:
Each affiliate that generated a product sale the day before gravity is computed increases it by exactly one. If affiliate stops generating sales, his contribution to product's gravity will gradually decrease, until it reaches 0.105905 and then immediately drops to zero after N days. If somewhere along the way that affilate generates another sale, his contribution to gravity jumps back up to 1 and would start decreasing again.
On average affiliate's contribution to clickbank gravity number declines 4.073% per day when no sales are made. If you would like to be exact, it actually decreases 4% on most of the days, but there are days when it is not true due to rounding errors.
Automated clickbank gravity script adds up contributions of each individual affiliate to calculate the final number.
Please keep in mind that following things are not taken into account:
Below you can see a graph of single affilate's contribution to the number if he made a single sale and then didn't make any sales at all
"Single shot" products
If you have been around clickbank for a while, you have probably seen a gravity chart that looks like this. This usually happens when two conditions are true:
A product is created. Promotional emails are sent out. People buy products though their own affilaite links and gravity skyrockets on the very first day. Of course each affiliate only buys the product once and does little to promote it. However the product gets noticed due to it's high gravity and generates some additional sales before going off-line so the gravity doesn't drop as fast as it could have otherwise. In this particular case it looks like the vendor released an update later down the road and sent out another promotional email causing a second (relatively) low gravity spike. The height of this spike roughly corresponds to the number of clickbank affiliates who purchased the product for themselves.
Highest gravity since I have started to keep records back in 2007 was achieved by Mass Money Makers. It achieved a whooping gravity of 2086.87 on January 10th, 2011
Which clickbank products should I promote then?
There is no exact answer here - it's all trial and error. High gravity usually indicates high competition. But this alone shouldn't stop you. 5% of affiliates usually generate 95% of the sales so the remaining 95% don't put up much of a fight. Low gravity doesn't mean small sales volume either. Single affiliate can still sell 100s of copies per day. So what should you do? Here are some guidelines that will hopefully be of some help: