Mary Weinstein is an Account Manmager at CPC Strategy specializing in Comparison Shopping Engine, and PLA management with an emphasis on individualized merchant attention.

Amazon and Google Shopping are major heavy hitters in the comparison shopping and ecommerce arena. This year, Google Shopping’s switch to paid cost per click listings on Google Shopping through Product Listing Ads has switched up the rivalry even further.

CPC Strategy analyzes data across the comparison shopping engines (CSEs) each quarter based on metrics such as cost per click (CPC), traffic, conversion rate (CR), and revenue for online merchants.

This last quarter, Q4 2012 the engine data is quite varied for the CSEs, most notably Google Shopping and Amazon Product Ads.

Cost Per Click: Google vs. Amazon

In the war for Q4 dominance, Google Shopping won out with cheaper cost per click (CPC) rates.

For Google, Q4 was the first fully paid quarter in Google’s history. However, Google’s average $0.31 CPC for Q4 2012 was still cheaper than Amazon Product Ads average CPC of $0.41. Overall, Google Shopping was 32.5% cheaper CPC than Amazon for the holiday quarter.

Conversion Rate: Google vs. Amazon

Google Shopping has seen a steady decrease in conversion rate metrics since 2011, with a 22.35% decrease from Q4 2011 to Q4 2012.

Inversely, Amazon Product Ads saw a 57.5% increase in conversion rates, from 1.8% in Q4 2011 to 2.8% in Q4 2012.

Traffic: Amazon vs. Google

Although Google Shopping is now charging for its traffic, that isn’t stopping consumers from shopping on the engine. Google Shopping sent 96% more traffic to sellers compared to Amazon Product Ads in Q4 of 2012.

Compared to the previous quarter, where Amazon dominated traffic generation.  Google sent merchants 144% more traffic than Amazon Product Ads in Q3 2012, when the transition to a commercial Google Shopping took place.

Check out the full Rankings to see additional engine metrics such as cost per sale.