Most of them don't understand how the platform optimizes.
I've been doing it since 2008, here's what they're missing:
On an optimized platform, it doesn't work that way.
They deliver based on relevance,(estimated) ability to achieve the desired action, auction competition, and bid.
If you have a variety of ads, you can see that some ads will deliver more to older users, others to younger.
Some ads will deliver more in feeds, others in stories.
This variance is at the ad level, not the ad set, account, or page.
Some placements naturally have higher CTRs, while others naturally have lower ones.
Some locations have more available inventory while others are more competitive.
The more users (inventory) available, the cheaper that variable can be, but the more competition for that variable, the more expensive it will cost.
Desktop feed users might be more likely to convert.
So then why not spend more there?
The inventory is limited and there's more competition, so it's more expensive to get those more valuable clicks.
The algorithm optimizes for this automatically. The more you spend, the more your costs will increase. Spending more means competing in more auctions.
Facebook wants to show users better and more relevant content. You get a discount for that. More relevant ads can win ad auctions at lower costs.
This relevance isn't a static metric. Relevance is a dynamic concept. Each ad can be more or less relevant to different swaths of users in your audience.
This is why people say "target with your creative"
Older men in California watching IG Reels on iPhones VS Younger women in Nebraska on FB on desktop computers
You couldn't accurately assess which one of those would have better performance because you can't break down the data that granularly.
You can't know how the users act, how relevant the ads are, or what the competition is like for each, but the algo can.
Same goes for placements and other attributes.
You're competing for attention with other types of advertisers who aren't optimizing for the same objective as you.
CPC, CPM, CTR, CVR, hook rates, etc are all dependent on those variables and relevance to the audience. The algorithm is trying to get you the most efficient conversions regardless of these secondary metrics.
Ad A might hit the goal CPA by going after a larger and cheaper less relevant audience.
Ad B might hit the same goal CPA by going after a smaller and more expensive but more relevant audience.
As an example, let's compare women 45-54 vs men 25-34:
(but maybe not at the same scale)
Sure, you can "target with your creative" but you can't control who it resonates with or which audiences are more
Maybe you made an ad for men 25-40 in cities, but it might resonate better with women 65+ in suburbs or that's where it can be delivered most effectively.
If you're trying to get a $25 CPA and your CPC is $8, that's a bad sign that you're getting a lot of things wrong.
Also, if you're using 7dc1dv attribution and see a $8 CPC and ~$25 CPA, there's a good chance FB is delivering to users already in the funnel and those are non-incremental view conversions.
If you believe that cheaper CPMs and cheaper CPCs lead to cheaper CPAs on FB, then you'll optimize accordingly and you'll spend more on ads with lower CPCs. At scale, your data will support your own stance.
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