A Regression-Discontinuity Analysis of 61,482 Trade-In Lines at a Trading-Card Chain
A research poster from the School of Continuous Improvement tests the density of keyed catalogue values either side of the $30 premium-tier line in a national trading-card chain's trade-in schedule, across 61,482 lines at 19 stores over 22 months. Lines keyed at $30.00-$30.99 run 2.70 times the fitted density while the two dollars below run 0.40 times, with placebo cutoffs at $25 and $35 returning nothing; the same cards' later resale prices pass smoothly through the line, and the estimated effect of crossing it on resale margin is indistinguishable from zero. Each store's Premium Tier Share, the measure its quarterly stock-quality ranking is built from, tracks its excess mass at the line rather than its realised margin.
| Authors | Joost Nwosu , Ingeborg Nwachukwu , Thandiwe Solberg |
|---|---|
| School | School of Continuous Improvement |
| Output type | Research poster |
| Funding | Indicator Stewardship Seed Fund: Auditing Whose Personal Best Still Sits on a Junior Swim Squad's Results Board ( $284,913) Indicator Stewardship Seed Fund: Reconciling a Community Hall's Key Register Before Nobody Can Say Who Holds One ( $274,158) |
| Published | |
| DOI | 10.5555/slop.lyel59 |
| Pages | 1 |
| Cited by | 30 outputs |
| Version | 1.0 |
| Licence | CC BY 4.0 |
Cites
Cited by
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- The Joke Was Never About You
- It Never Takes Your Word For It
- What Is A Performance Review Actually For?
- The Stamp-Card Coordinator's Audit Taught Counter Staff to Pass the Checklist, Not Earn the Stamp
- Present, Not Managing
- Measuring the Twelve-Item Line
- Towards a Portable Entitlement Standard
- CUT
- Which Closing-Down Sale Is Actually Closing?
- CUSP
- Measuring What Outlives Its Reason
- Equal Turns. Uneven Buses.
- Does the Lock Close the Loop?
- Below Threshold, Beyond Appeal
- Towards a Coefficient That Travels
- Towards Report-Blind Triage
- The Same Ninety-Eight Per Cent, Read Three Ways
- Carried Forward, Unopened
- Towards Self-Resourcing Crossing Supervision
- TIER
- A Cent Under the Limit
- Rounded Up, Fully Booked
Cite as
@misc{slop_lyel59,
author = {Joost Nwosu and Ingeborg Nwachukwu and Thandiwe Solberg},
title = {Nothing Happens to a Card at Thirty Dollars: A Regression-Discontinuity Analysis of 61,482 Trade-In Lines at a Trading-Card Chain},
year = {2026},
publisher = {Slop University},
doi = {10.5555/slop.lyel59},
url = {https://slop.university/outputs/slop-poster-a-regression-discontinuity-and-lyel59/},
version = {1.0},
note = {Research poster},
}