There are a number of different ways in which CSS and merchants can agree to work together. Any given CSS might offer multiple service models or tailor services to your specific needs. CSSs offer different areas of expertise, services, and charging models. Some specialize in specific categories (apparel, for example). Some manage feeds and campaigns for you, while others provide tools for you to manage your product data and bidding strategies yourself. Hybrid models exist as well, and CSSs may offer a variety of additional services.

Some CSSs charge a fee per click, while with others you might pay a commission when a click on an ad leads to a sale. Combining the strengths of several CSSs can increase the overall performance of your Shopping ads. You need to work with at least one CSS to place Shopping ads; you can work with several at the same time if you prefer. Some merchants wish to compare campaign performance between different CSSs. Along with all the differences of various service models, we understand that merchants may want to conduct a test for the shopping campaigns.

To set up such a test in the most fair way for both Google CSSs, we recommend reviewing the few factors outlined in this post.

Defining your goals and KPIs

Before considering a test between CSSs we strongly recommend you to review the objective of the test. The Shopping ads auction is CSS agnostic. As a result the exact same setup between 2 CSSs (new and identical Merchant Center feeds, new and identical Google ads campaigns, same budgets, same bids placed in the auction) will provide the same performance results. We recommend starting with an identical setup (including bid level in the auction) to check performance and ensure setups are comparable at the start.

Setting the campaign up

Determine the test period: We recommend testing at least 6 weeks up to 3 months because it gives time to evaluate the difference between optimisation strategies.

In order to have the most trustworthy results from the test it is very important to start with identical conditions. Here are some recommendations you can apply:

  • The merchant creates a new Merchant Centre with CSS 1 and CSS 2 (please check “opted in the property and beyond search” option to ensure identical setup)

  • Upload the exact same product data in the two MCs. We recommend a small portion of the inventory to limit the impact of the test on the merchant’s business. All product data must be the same.

  • The merchant should create two brand new campaigns, one per Merchant Center, and build the exact same campaign structure.

  • Set campaigns corresponding to both Merchant Center accounts with comparable settings including geo targeting, language and budgets.

  • Once you can confirm that all aspects of both set-ups are comparable (in order to ensure that the testing scenario is fair), CSSs can start optimizing.

Evaluating the Result

In evaluating the different services provided by CSSs during these tests, for example optimisation techniques, make sure that the campaigns have the identical setup when the test starts (such as geography selection, set of items to be advertised). From there on, CSSs can start with their own optimisation techniques. This is important to make sure the merchant can ultimately make their decision based on how one CSS has optimised compared to the other.