Google’s official measurement guidance urges advertisers to combine media mix models, incrementality experiments, and attribution into a single framework to steer their campaigns. On a slide deck presented to a board, this triad looks mathematically unassailable. In an ad account spending $80,000 a week, it is an operational trainwreck. Econometric models built on aggregate historical spend cannot tell you whether to increase your Performance Max target ROAS by 15% on a Tuesday
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The 90-Day Lag: Why Media Mix Modeling for Campaign Optimization Breaks Your Bids
Google claims you can steer campaigns with MMM and attribution combined. In reality, feeding macro econometrics into daily bid strategies breaks your account.
September 8, 20261 min readPublished by Gamal Hemdan
What This Means for Your Account
This update directly affects your campaigns.
Check your campaign-level conversion lag report in Google Ads right now (Tools & Settings > Measurement > Attribution > Path Metrics). If your median time to convert exceeds 14 days, forcing weekly target ROAS shifts based on media mix modeling outputs will throw your Smart Bidding portfolio into continuous exploratory learning.
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