I have been using Google Analytics for e-commerce tracking it is very helpful but when I compare my product performance with my sales performance there is a difference in the revenue figure. I can not figure out why it shows like that. Can anyone suggest an possible reason for it.
Re: Ecommerce Tracking
Ecommerce data is pushed to GA in two separate pieces.
1st you have the transaction which can include things like shipping and tax.
2nd you have the transaction ID from the first piece and the product arrays that contain the product id, name, item price and quantity (and more info for enhanced ecommerce). Note shipping and tax is not passed in the product array.
If all is implemented properly (garbage in, garbage out), the only difference you would expect to see is that transaction revenue would include shipping and tax (if passed into the transaction data) and the product revenue would not include this amount. So hypothetically, if you have a transaction for $116 which includes $10 for shipping and $6 for tax; you should be able to drill down into the products and see that 2 $50 items were purchased for $100. Hence the difference in revenue for a properly coded implementation.
In reality, there are many things that could be happening to distort this on the implementation (coding) side; e.g. product level deductions that are not reflected in the value passed to the transaction, etc. etc.