With every product in the ClickBank Marketplace there are a number of stats one of which is gravity.

Here is ClickBank's explanation of gravity

*Gravity is a performance statistic - a number
which represents a unique calculation by ClickBank that takes into account the number of different affiliates who earned a commission by promoting this product over the past 12 weeks.*

* Since more recent transactions are given a higher value, this number can give you an idea of what products are “hot” at the moment, in terms of being promoted by many affiliates and making a good number of sales. However, high gravity can also indicate that there will be a lot of competition in promoting this product*

__The calculation__

ClickBank does not give details of the calculation but it is widely thought to be as follows.

A sale made in the current week is assigned a gravity of 1, reducing to 0 after 12 weeks.

Thus 0.91 for week 2, descending to 0.08 in week 12.

What we can deduce from this is that
the gravity figure represents the **minimum**
number of affiliates who have made a sale
in the 12 week period. In other words a gravity
of 100 indicates that at least 100 affiliates have
made sales. The true figure cannot be determined.

__Relationship to number of sales__

Gravity has NO BEARING on the number of sales.

An example will show this.

Using the algorithm whereby a gravity value of 1 is given to a sale made in the current week consider these two situations:

Product A: 100 affiliates make 1 sale each

Total sales = 100

Gravity = 100

Product B: 1 affiliate makes 100 sales.

Total sales = 100

Gravity = 1

So we can see that two products with vastly different gravities produce the same number of sales.

On the face of it gravity gives us a __weighted__ number of affiliates who have recently made a sale - so that we can get an idea of the competition.

However bear in mind

a) It does not say how successful these affiliates are. Whether an affiliate makes 100 sales or just one sale the gravity is the same.

b) Gravity is only a measure over the last 12 weeks and may be particularly high due to a big launch of a new product or a big promotion of an existing one.

c) The vendor may have many additional products in the Marketplace account and the stats don't represent the product listed.

d) To make it even more difficult to determine the true value of gravity look at the next section . . .

If a vendor wants to increase gravity he could

1) Set up different affiliate accounts then

a) use them on a rotating basis for his own vendor sales

b) buy his own product through each of them

2) Ask his affiliates to purchase the product through their own accounts and

a) throw in a compensatory bonus

b) reimburse their payments outside of ClickBank

Methods 1b and 2b may be regarded as unethical

If you want to ensure that high gravity is not due to a one-off surge you can check the gravity history with a service such as CBENGINE

Given that so many affiliates will search for high gravity products in the mistaken belief that they are big sellers it makes sense for you to maximize the gravity of your product.

You could make a one-off promotion drive to existing and new affiliates. Then as the gravity rises and the Marketplace ranking soars other affiliates will in turn be induced to sign up and so on.

Some of the key factors you should consider when selecting a product to promote are:

1. The amount of commission you will receive. Here is a calculator.

2. How effective is the sales page

- does it convert well (with low refund rate)

- are there sales page leaks whereby you will
lose commission

3. Is it an in-demand item

4. Check out the affiliate support

Note that you cannot obtain conversion or refund rates from the ClickBank stats. You need to judge the quality of product and sales page for yourself.

For a more detailed look at selection criteria see the free book ClickBank for Newbies

**So where does gravity fit in ?**

Well one other factor you might want to consider is the competition from rival affiliates. This is especially important in search engine marketing where high ranking on keywords is vital.

Therefore you should be seeking a LOW gravity product indicating fewer affiliates.

__Vendors:__ Gravity is IMPORTANT

Try to maximize gravity to attract affiliates

__Affiliates:__ Gravity is of LITTLE IMPORTANCE

* it tells you little about sales - and nothing about the conversion rate

* high gravity indicates lots of affiliates with recent sales but not how successful they are and figures may be just one-off spikes or even manipulated

* low gravity indicates few affiliates so can be useful if you are seeking less competition