Recently I’ve been researching multi-channel bidding problems. Quoting Google Ads’ Power More Conversions and Value through Cross-Channel Bid Optimization:
Traditionally, advertisers have applied automated bidding to campaigns that target a single channel. For example, they might use a bid strategy that maximizes conversion value on separate campaigns for Search, Display, and Video. But there are limitations to this siloed approach. But multi-channel bid optimization can help you to drive better results compared to single-channel bid optimization by maximizing marginal CPA or ROAS in each and every auction
Simply put, when a campaign runs across more traffic positions simultaneously, budget marginal utility can be better optimized. This is intuitive - with richer traffic inventory, the same budget can theoretically achieve better efficiency. This is similar to “universal delivery” products recently launched by various domestic media platforms. These products provide lower-barrier solutions for advertisers, saving budget allocation or bid setting across channels, while platforms use algorithmic capabilities to improve budget efficiency.
From a technical perspective, multi-channel raises two questions:
- Is unified bidding optimal? If not, how to do per-channel bidding
- Should budget be explicitly allocated to each channel
The multi-channel examples above are all within one large platform, where budget and bidding across channels can be easily shared. Another common multi-channel definition is cross-platform, e.g., advertisers running on both Google and Meta, where budget and bidding clearly can’t be shared. From the advertiser’s perspective, how to optimally allocate is also worth discussing.
This article mainly discusses the former: budget allocation and bidding when running on multiple channels within the same platform. Also briefly mentions research on cross-platform scenarios.