Following on from my researches into different conversion results from Google Analytics and Adwords  I also remembered that you can change the tracking parameters for Google Analytics.

This uses a little bit of code, a parameter called utm_nooverride. It is appended to the end of URLs like this: http://www.yoururlhere.com/landingpage&utm_nooverride=1

This basically stops the more recent click overwriting the "Source" information for the visitor. This stops the "last referrer" getting the sale/conversion, which normally happens in Google Analytics.

There are basically two situations in which you might want to use this parameter. The first is in emails to your house list. This means if someone converts as a result of an email, you actually track them back to how they originally found you. You can see how useful this could be if you are trying to track the ROI from the original source and not the ROI of your email programme.

Secondly, as explained in this ROI Revolution article you can use it on your branded Adwords. Again, this is a technique to track the original visit to your site (the one when they found out who you were) and not any subsequent visits where they click on the Adword for your company name to return to your site. This is useful if you are not a well known brand and are interested in tracking sales back to the original "long tail" keyword, especially if you have the sort of product or service that people don't buy on the first visit but instead research and refine their shortlist before making a purchase.