From Shopify Wiki
Google Analytics is a brilliant and free web traffic analyzation tool. It allows you to extract every bit of information from your web traffic possible. Unlike the Shopify internal statistics, it is not real-time and can sometimes take 24 hours to update, so both these systems have their independent uses.
Shopify has excellent support for Google Analytics.
- Before getting started, please See our Screencast:http://vimeo.com/1921553?pg=embed&sec=1921553&hd=1
To get started you will have to get some information from Google Analytics and enable the e-commerce tracking feature.
To start, please login to your Google Analytics account.
Configuring Your Profile
In this screen you need to enable E-Commerce website and correct the currency and other options you see:
Click save and you will land back on the tracking, here we click on check status or similar
Entering the Tracking Name in Shopify
All done! We can take our Google Analytics Account id now and tell Shopify about it. Go to the Preferences screen and enter your account ID in the provided text field.
Shopify will now automatically add the proper Google Analytics tracking codes to all of your pages. You should see e-commerce tracking appear the next time Google Analytics updates.
Double Check that you've enabled ECommerce tracking
Click here for the Google Analytics Help article showing how to enable e-commerce tracking.