Running Google Ads + Meta Ads + SEO – how do you actually know what’s working?

Here’s my attribution headache right now:

1. Someone finds us via Google Shopping (paid)
2. Leaves, then sees a Meta retargeting ad
3. Comes back later via Google organic
4. Buys

GA4 says “organic” so SEO gets the win. Google Ads says “Shopping campaign” so paid search claims it. Meta says it “assisted” the sale.

On paper every channel looks great, but the bank account doesn’t care about who takes credit – only about which channels actually produce profitable customers.

For people running Google Ads + Meta + SEO at the same time, how are you deciding where to put more budget?

Are you going off last click, some kind of blended MER/POAS, or do you have a separate attribution setup that you actually trust?