Names and aliases
TTFQL, time to first eligible supply unit
Formula
median(timestamp_of_first_eligible_unit − timestamp_of_cohort_entry) per cohort, with censored observations retained explicitly
Metric card
| Unit | hours or days, reported as median and selected percentiles |
|---|---|
| Data source | Cohort-entry events, supply-creation events, eligibility and moderation checks, and matching-availability flags. |
| Frequency | By registration or admission cohort, with the observation window fixed in advance. |
| Segments | micro-market, category, acquisition channel, seller type, creation method, cohort |
Interpretation errors
- Averaging over completers and dropping sellers who never produced an eligible unit, which discards the worst part of the cohort and flatters the metric.
- Taking the draft-creation timestamp instead of the moment the unit became available for matching.
- Comparing cohorts observed over windows of different lengths.
Example
Illustrative example: a cohort median of 26 hours with 35% of observations censored at a 14-day window boundary. The numbers describe no real platform.
Use
The metric fills the gap between registration and activation: seller activation rate answers what share of a cohort reached useful participation, while this measure answers how quickly those who reached it did so. Publish the median and percentiles together with the censored share and the window length, or cohort comparisons are invalid. Read the distribution by creation method: bulk upload and manual creation produce different profiles, and mixing them hides the onboarding bottleneck.
Anti-example
A shorter median after listings are generated automatically from an external catalogue looks like better onboarding, yet supply can reach the market faster and still receive no exposure and no responses. The metric cannot be interpreted apart from zero exposure share and unmatched supply share.
Limitations
- The metric measures how quickly supply reaches the market and says nothing about its quality or the demand for it.
- Values are sensitive to moderation rules: faster review shortens the time without any change in seller behaviour.
- Censored observations must remain visible; without them the median is systematically understated.
Related metrics
seller-activation-rate, time-to-first-transaction, unmatched-supply-share, zero-exposure-share
Context sources
These works provide two-sided-market context; the formula above remains an author-defined working definition.
- Geoffrey G. Parker, Marshall W. Van Alstyne. Two-Sided Network Effects: A Theory of Information Product Design (2005).
- Kong-Pin Chen, Yen-Chi Huang. A Search-Matching Model of the Buyer-Seller Platforms (2012).