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Facebook CBO algorithm favoring more expensive CAC ad sets…
Maybe I’m missing something here.
I find myself wondering about CBO and its effectiveness pretty often.
Some times I’ll have three ad sets in a CBO campaign showing a similar data set to the following:
Ad set 1:Total spend $1500, $10/purchase
Ad set 2:Total spend $4000, $12/purchase
Ad set 3:Total spend $1150, $6/purchase
And Facebook’s CBO will be optimizing for *ad set 2* with an overwhelming focus. It will be spending $10/day on the perceived better performing *ad set 3* and $490/day on *ad set 2* which is perceived to be twice as expensive.
With a limited budget I need CBO to be focusing on lower cost per purchase which I thought it would.
I would’ve expected the algorithm to funnel my daily budget to those lower CAC ad sets and only stop if the CAC rises and thereby makes it more expensive then some other ad set on the CBO.
Am I missing something here? Why does facebook not favor perceived lower CAC ad sets?
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4 Replies
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I am seeing the same thing and cannot get a straight answer from Facebook. I was essentially told by our rep that its inevitable that everyone will be switched over and that I just need to let the algorithm do its thing…
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I was told the reason this happens is because the algorithm knows that increasing spend to ad set #3 would also increase the cost per purchase. So, in your example, spending anymore than $10 per day on ad set #3 would cause the cost per purchase to increase (say to $14).. Whereas, ad set #2 can support much greater spend while maintaining the $12 cost per purchase.
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Are there significant audience size differences between the ad sets?
FB does a pretty good job of balancing costs and scale, in my experience. so if one adset is website retargeting and another is a lookalike audience, the lookalike will get more spend because the size is significantly different.
you can always just pause the underperforming top spender and force spend to the better performer, or break them out to their own campaign and control the budget splits
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it’s very likely that Ad Set 2 has the largest audience… Ad Set 3 is pretty much low-hanging fruit and any additional spend will spike the CPA
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