Google is adding multi-campaign testing with the new Mix Experiments beta

Google is releasing Campaign Mix Experiments (beta), a new testing framework that lets marketers test multiple campaign types, budgets, and settings within a single, integrated experiment.
How does this work:
- Advertisers can create up to five experimental armseach containing a different mix of campaigns.
- Campaigns can come from multiple arms, depending on the traffic between them.
- Test support Search, Performance Max, Shopping, Demand Gen, Video, and app campaigns (except hotels).
- Traffic segmentation is customizable (minimum 1%), with typical results being a very low segmentation for fair comparison.
What to check:
- Budget allocation in all types of campaign
- Account structureincluding integration versus fragmentation
- Bidding strategies, targeting, and feature acceptance
- Interoperability of different channelsnot just the height of one campaign
Why do we care. Instead of testing Search, Performance Max, Demand Gen, or Video campaigns alone, marketers can now see how different campaign types work together – and which mix delivers the best business results.
Reporting details. Results appear in test summary and campaign level reporting, with marketers able to choose confidence intervals (95%, 80%, or 70%) and key success metrics such as ROAS, CPA, conversion, or conversion rate.
Best practices:
- Keep test arms the same, change one variable at a time.
- Compare the total budget for all weapons unless the budget is the test itself.
- Avoid shared budgets and major flight changes.
- Do the tests for at least six to eight weeks to achieve statistical reliability.
Between the lines. Google acknowledges that modern operations aren’t about winning a single campaign — it’s about getting it right combineespecially since the default blurs the lines between channels.
Bottom line. Campaign mix testing gives marketers a clear, realistic way to assess how different campaign types and budgets work together – and make smarter decisions about where spending money delivers the most value.
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