A quick primer
There's no dedicated "signal overlap between asset groups" report — worth stating plainly so you're not searching for a tool that doesn't exist. But overlap can be assessed indirectly through asset group reporting: it lets you review status, Ad Strength, conversions, conversion value, and audiences across each asset group in the campaign — an audience column exists, it just has to be cross-referenced between groups by hand rather than read off as a ready-made overlap metric.
There's an important methodological caveat worth keeping in mind here: asset groups with a higher CPA or lower ROAS still contribute to goals, and Google specifically advises against removing an asset group on that basis alone — the guidance instead points to marginal, rather than average, ROI. That means even if signal overlap genuinely exists and one group gets less traffic/converts worse on the shared segment, that alone isn't grounds for immediate action — confirm the cause is really overlap before treating a lower average as a problem.
The same underlying principle used for listing groups applies to signals too: asset groups ideally shouldn't overlap on the segment they're targeting — products, audience, or semantics — or they end up competing for the same traffic inside the campaign, and that overlap is the first thing worth checking before diving into finer-grained metrics.
What to check before you touch anything
- Whether signal types match between groups (customer lists, custom segments, demographics, additional segments) — not just whether signals exist, but whether they're identical in composition.
- Whether the groups overlap on products/semantics at the same time as signals — overlap on multiple axes at once strengthens the case for real internal competition, rather than merely similar-but-distinct segments.
- How traffic and conversions split between the groups via asset group reporting — a stable, clear skew toward one group with similar signals can be an indirect sign of overlap.
- Whether decisions are being based only on each group's individual CPA/ROAS — Google specifically warns against removing groups on that basis alone without broader context.
- How recently and how often each group's signals were changed — if one group was recently reconfigured, a performance gap may reflect a learning phase rather than overlap.
Possible approaches
- Cross-reference signal composition (not just presence, but the specific lists/segments) across every asset group in the campaign manually through asset group reporting — the closest available method for assessing overlap without a dedicated tool.
- If overlap is confirmed on both signals and products/semantics — separate segments along both axes at once, since partial separation (products only, say) may not resolve the competition if signals remain identical.
- Don't decide to delete or merge an asset group based solely on one group's weaker CPA/ROAS — confirm real signal overlap first, rather than relying on "this group looks worse, so it must be redundant" logic, which directly conflicts with Google's own guidance on marginal return.
- If signal overlap is minimal but traffic competition is still observed — look for the cause on other axes (products, semantics, search themes), since signals are only one of several variables shaping an asset group's targeting.
- Periodically revisit signal composition as the number of asset groups in a campaign grows — the risk of accidental overlap increases with every new group added, especially if groups were created at different times by different people without cross-checking existing ones.