Putting aside the -most important- variables of audience and creative, how much control do you have over your campaigns?
Channels tend to take away as much control as possible from you. That’s why Facebook has an Auto Bid option and moved the budget at the campaign level. That’s why Google and Facebook has a dynamic ad type, where you put the images and text, and they will find the best combination. That’s why Facebook recommends Automatic Placements.
I’m not saying that having less control is a good or bad thing. If you think about it, Google and Facebook have data that you don’t, more computing power, and better algorithms to find the best combinations.
Much of what a media analyst do in their day to day, is to refresh audiences and creatives (if you find someone who can beat Facebook’s performance, by updating bids and budgets, you should definitely hire her.)
Take the following example: a Facebook campaign that ran for 2018, where the Ad Set budget was refreshed daily. Assuming the marketing (audience + message) was right, see the covariance between Ad Set Budget, Spent, and the Volume/CPA:
This is particular to the marketing behind the campaign. What’s interesting to see is that the more you spend, the higher is the CPA. Spending less or more is not an option, so again, you either change the audience or refresh the creatives.
If you want to run the analysis above with your own dataset, you can use this python script.