Target-based bidding: did budgets become the constraint?
Tyler Rhodes reports a comparison covering about $2.7 million in spend over 26 weeks. Campaigns using tCPA or tROAS showed higher budget-lost impression share without the same CPC divergence reported elsewhere. Lead volume and efficiency were stable in his sample.
A useful prompt to examine bidding-strategy cohorts and measurement compatibility before attributing account changes to Google’s August update.
Started by Tyler Rhodes on LinkedIn. Replies belong to their original authors.
Observational account data reported by the author, not an independently reproduced experiment. The comparison group mixes bidding strategies. An exact publication date was not exposed in the inspected post. External discussion; not a Paid Media Collective member post.
Read the challenge analysis
What the discussion adds
Rhodes reports budget-lost impression share rising from around 1% to 29% for the target-constrained cohort, versus 18.7% to 21.2% for campaigns without a target. His explanation is that budget became the binding constraint. These are reported observations, not proof that the platform update caused the difference.
The main measurement caveat
Mike Ryan questions whether the comparison includes Maximize conversions and Maximize conversion value. Rhodes confirms that the group mixes strategies outside tCPA and tROAS, including manual and other maximum-bid strategies. Google warns against using Lost IS (budget) with Maximize conversions: these maximize strategies aim to spend the set budget, which the column does not account for. The mixed group therefore cannot serve as a clean control for that metric.
What is still missing
The accessible post does not provide exact account and campaign counts, geography and sector mix, weighting, variance, conversion definitions or attribution windows. Rhodes acknowledges launches, pauses and other changes. Stable lead volume and efficiency need their measurement definitions and conversion-lag treatment before readers can assess the result.
How to strengthen a follow-up
Compare fixed weekly cohorts, separate target-based, maximize and manual bidding, and split target-based campaigns by budget limitation. Report both spend-weighted and campaign-level results alongside CPC, CTR, conversion rate, CPA or ROAS, and actual spend against budget. Record budget, target, tracking and campaign-mix edits. A suitable holdout or matched pre/post comparison would improve the evidence, with a longer follow-up after conversions mature.
What members can contribute
Share the bidding strategy, campaign type, date window and relevant account changes behind any comparison, using aggregated figures that you have permission to disclose. Keep campaign outcomes separate from impression-share diagnostics. Read the original post and chart, including the author’s reply, before applying the hypothesis to your own accounts.