Names and aliases
zero-impression supply share, dark supply share
Formula
eligible_supply_with_zero_qualified_exposure / eligible_supply × 100%
Metric card
| Unit | % of eligible supply |
|---|---|
| Data source | Eligible-supply snapshots, candidate-set logs, qualified impression events, eligibility rules, and window boundaries. |
| Frequency | By supply cohort and operational matching window. |
| Segments | micro-market, category, geography, price, quality, cohort, ranking surface |
Interpretation errors
- Reading zero exposure as absent demand when the unit never passed eligibility or entered a candidate set.
- Merging technical unavailability with a ranking decision not to show the unit.
- Computing the share over the whole catalogue instead of eligible supply, which understates the value.
Example
Illustrative example: 24 of 200 eligible units received no qualified exposure, producing a 12% share. The numbers describe no real platform.
Use
Treat the metric as a lower bound on the allocation problem: a unit that never entered a candidate set had no opportunity to meet demand, whatever its quality. Separate the three causes of zero exposure — eligibility mismatch, absent relevant query, and ranking decision — because each calls for a different operational response. Report it beside exposure coverage: coverage answers how much supply received enough attention, zero exposure share answers how much received none at all.
Anti-example
A lower zero exposure share after adding a randomised rotation slot does not demonstrate better matching. Units gained impressions, but if the qualified response rate did not move, what changed is the distribution of attention rather than the market’s ability to connect the two sides.
Limitations
- The value depends entirely on the definition of qualified exposure and on window boundaries; cross-platform comparison without a shared definition is meaningless.
- Zero exposure describes the distribution of attention, not the market value of the supply unit.
Related metrics
exposure-coverage, exposure-concentration, unmatched-supply-share, qualified-response-rate
Context sources
These works provide two-sided-market context; the formula above remains an author-defined working definition.
- Jun Li, Serguei Netessine. Higher Market Thickness Reduces Matching Rate in Online Platforms: Evidence from a Quasiexperiment (2019).
- Hanna Halaburda, Mikolaj Jan Piskorski, Pinar Yildirim. Competing by Restricting Choice: The Case of Matching Platforms (2017).