Savings
Sunk-cost export hysteresis is one of the most established results in the field. Roberts and Tybout (1997), Das, Roberts and Tybout (2007) and Besedes and Prusa (2006) showed that prior experience raises the probability of exporting again and that the advantage decays with time out of the market. Nothing here overturns that, and the finding that a lapsed capability re-enters more often than a virgin one is their result, not ours.
Two things the hysteresis literature does not provide are on this page. The first is a density-matched contrast on the full panel: 233 BACI country codes by 4,615 HS6 products present in every year, 29 year-to-year transitions, 2,762,318 presence cells, with the comparison held inside product-space density bins so that the lapsed cells are compared against virgin cells the country is equally close to. The second is a fitted functional form for the decay, tested against the alternative and then broken apart to see whether it is an artefact of pooling.
What the precompute killed
Four claims in the original design did not survive their own run and are corrected here rather than quietly dropped.
- The multiplier is not five. Two defensible standardisations disagree: density deciles with years pooled gives 3.78, year by density strata gives 4.68. Neither reaches five. Five is reachable only in the single latest transition (5.01 for 2023 to 2024) or crudely with no density control at all (5.56). The headline is published as a range.
- The functional-form verdict flips on the strict savings measure. On the raw re-entry hazard the power law wins decisively. Subtract the never-held baseline of 0.0125, which is exactly what an Ebbinghaus savings measure is, and the exponential wins. A constant plus an exponential mimics a power law in logs, which is a form of the Anderson and Schooler critique this instrument is borrowed from. Both races are published.
- The advantage dies at 21 years, not later. Density-standardised, the lift is 1.78 at an eleven-year gap and 1.38 at fifteen, both with confidence intervals excluding 1. At 21 years the interval first contains 1 (0.988 to 1.115). Anything stronger than "more than a decade" is not supported.
- The balanced-core restriction is not load-bearing. Dropping it entirely, so that all 5,022 catalog codes sit in the grid every year, moves the crude lift from 5.5562 to 5.4623 (1.7%), the year-by-density lift from 4.6814 to 4.5964 (1.8%) and the density-only lift from 3.7788 to 3.6635 (3.1%). The restriction is right on principle, since a globally extinct code otherwise reads as every country exiting at once, but it does not carry the result and the page does not claim it does.
The contrast
A cell is one country and one HS6 product in one year. It is present when its revealed comparative advantage is at least 1.0, lapsed when it is absent now but was present in some earlier year, and virgin when the country has never held it. Pooled over 29 transitions, 4,880,148 lapsed cells produced 340,188 re-entries, a rate of 6.97%, against 23,628,298 virgin cells producing 296,445 first entries, a rate of 1.25%. That is a crude ratio of 5.5562 MEASURED. Crude is the wrong number, because lapsed cells sit closer to what a country already makes. Holding product-space density fixed the contrast falls to 3.7788 with years pooled (3.7598 to 3.7979) and 4.6814 with year by density strata (4.6554 to 4.7076) MODELED. Both are defensible, so the page publishes the range and not a point estimate.
Lapsed beats virgin in all ten product-space density deciles
The density-standardised lift, at every number of density strata
Every RCA cutoff strengthens the result; 1.0 is close to the most conservative
The lift rises monotonically with the cutoff, from 3.98 at RCA 0.5 to 5.45 at RCA 2.0. Choosing a stricter definition of "makes this product" makes the memory look stronger, so the reported figure at RCA 1.0 (4.68) is not cutoff-shopped.
The robustness ladder: the effect survives even for cells sitting just below the cutoff
Four ways to build the grid, at the same RCA cutoff of 1.0
| Specification | Lapsed cells | Rate | Virgin cells | Rate | Crude | Year x density | Density only |
|---|---|---|---|---|---|---|---|
| S1 Balanced core, full 233-code country grid every year | 4,880,148 | 6.97% | 23,628,298 | 1.25% | 5.556 | 4.681 | 3.779 |
| S2 Balanced core, country-years that report in both y and y+1 | 4,714,800 | 7.22% | 22,366,399 | 1.30% | 5.567 | 4.703 | 3.783 |
| S3 Products traded somewhere that year, no balanced-core restriction | 5,181,280 | 6.86% | 25,213,652 | 1.25% | 5.500 | 4.598 | 3.704 |
| S4 All 5,022 catalog codes every year, no restriction at all | 5,344,458 | 6.65% | 25,821,238 | 1.22% | 5.462 | 4.596 | 3.664 |
No specification sits more than 3.1% away from the published S1 on any of the three estimators (1.7% crude, 1.8% year by density, 3.1% density only). The choice of universe is not what produces the result.
The lift is not a period effect
The crude lift runs 5.65 to 10.47 and the within-year density-standardised lift runs 4.01 to 5.63 across 28 transitions, with no trend that would let one period carry the pooled result. The latest transition, 2023 to 2024, is the high end at 5.01 , which is the only place a multiplier of five is defensible.
How long the memory lasts
Density-standardised lift by years since the product was last held
Require a longer absence and the advantage decays to nothing
The shape of forgetting
Memory science does not only ask whether retention decays, it asks in what functional form. Wixted and Ebbesen (1991) put the power law against the exponential on human retention data and the power law won. The same race is run here on 28 gap lengths, weighted by cell count, in logs. On log-log axes a power law is a straight line and an exponential is curved, so the reader can see the answer without the R-squared values.
The raw hazard is power-law shaped
Subtract the never-held baseline and the exponential wins
The winner by fit window, 21 windows on each measure
| Window | b (raw) | R2 power | R2 exp | Winner | b (excess) | R2 power | R2 exp | Winner |
|---|---|---|---|---|---|---|---|---|
| gaps 1 to 5 | 0.7357 | 0.9977 | 0.9674 | power | 0.8356 | 0.9950 | 0.9754 | power |
| gaps 1 to 10 | 0.7619 | 0.9982 | 0.9239 | power | 0.9175 | 0.9920 | 0.9490 | power |
| gaps 1 to 15 | 0.7870 | 0.9970 | 0.9080 | power | 1.0093 | 0.9795 | 0.9528 | power |
| gaps 1 to 20 | 0.8043 | 0.9958 | 0.8950 | power | 1.1034 | 0.9572 | 0.9625 | exponential |
| gaps 1 to 25 | 0.8142 | 0.9951 | 0.8828 | power | 1.1972 | 0.9206 | 0.9713 | exponential |
| gaps 1 to 28 | 0.8153 | 0.9951 | 0.8771 | power | 1.2132 | 0.9157 | 0.9723 | exponential |
| gaps 2 to 10 | 0.7998 | 0.9996 | 0.9534 | power | 1.0080 | 0.9964 | 0.9716 | power |
| gaps 2 to 15 | 0.8268 | 0.9984 | 0.9439 | power | 1.1247 | 0.9837 | 0.9771 | power |
The kill condition, run
A pooled power law proves nothing on its own: average a set of exponentials with different rates and the average is approximately a power law, whatever the parts are doing. That is the Anderson and Schooler critique, and it is the reason the disaggregated fits are a precondition for publishing this page rather than future work.
The exponent under disaggregation, both measures
| Measure | Level | Groups | Pooled b | Median b | IQR | Range | b > 0 | Power wins (R2) | Power wins (LL) |
|---|---|---|---|---|---|---|---|---|---|
| raw hazard | country | 228 | 0.8153 | 0.7976 | 0.667 to 0.895 | 0.188 to 1.756 | 100.00% | 211 of 228 | 214 of 228 |
| raw hazard | density decile | 10 | 0.8153 | 0.7213 | 0.668 to 0.745 | 0.635 to 1.316 | 100.00% | 10 of 10 | 10 of 10 |
| raw hazard | section | 21 | 0.8153 | 0.8072 | 0.767 to 0.840 | 0.642 to 0.886 | 100.00% | 21 of 21 | 21 of 21 |
| excess hazard | country | 228 | 1.2132 | 1.0809 | 0.914 to 1.264 | 0.182 to 1.999 | 100.00% | 162 of 228 | 160 of 228 |
| excess hazard | section | 21 | 1.2132 | 1.1776 | 1.093 to 1.233 | 0.986 to 1.378 | 100.00% | 6 of 21 | 8 of 21 |
Raw hazard: every exponent positive at all three levels, and the power law wins in 21 of 21 sections, 10 of 10 density deciles and 211 of 228 countries, with the country median exponent (0.7976) close to the pooled one (0.8153). The page survives. Excess hazard: the power law wins in only 6 of 21 sections and 162 of 228 countries, so that claim is withdrawn rather than defended.
All 21 HS sections, raw re-entry hazard
The 17 countries where the exponential beats the power law on the raw hazard
| Reporter | ISO3 | Re-entries | b | R2 power | R2 exp |
|---|---|---|---|---|---|
| Eswatini | SWZ | 2,062 | 0.8211 | 0.9121 | 0.9376 |
| Guam | GUM | 1,798 | 0.7258 | 0.9232 | 0.9240 |
| Montserrat | MSR | 1,284 | 0.5813 | 0.6544 | 0.7879 |
| Serbia and Montenegro (...2005) | SCG | 1,123 | 1.7561 | 0.9092 | 0.9949 |
| Lesotho | LSO | 1,020 | 0.8779 | 0.8975 | 0.9140 |
| Burkina Faso | BFA | 991 | 1.3367 | 0.8614 | 0.8616 |
| Nauru | NRU | 762 | 0.5344 | 0.8357 | 0.8482 |
| Pitcairn | PCN | 694 | 0.4126 | 0.5753 | 0.6439 |
| Br. Indian Ocean Terr. | IOT | 652 | 0.3129 | 0.5965 | 0.6104 |
| Eritrea | ERI | 545 | 1.1291 | 0.8501 | 0.9257 |
| Mayotte (Overseas France) | MYT | 516 | 1.6031 | 0.8091 | 0.9701 |
| Tuvalu | TUV | 464 | 0.8299 | 0.8700 | 0.9116 |
Dormant capabilities, by country
The panel is a stock as well as a rate. For every 2024 reporter the build lists the products it held at some point since 1995, does not hold now, and would be most likely to regain: the ten with the highest re-entry hazard at their gap length, plus the five most complex by 2024 PCI. 226 reporters, 3,384 rows in the shortlist table.
Dormant capabilities and their re-entry hazard, Morocco
| HS6 | Product | Last held | Gap | Density decile | PCI 2024 | Hazard | Hazard, density | Listed by |
|---|---|---|---|---|---|---|---|---|
| 151219 | Vegetable oils: sunflower seed or safflower oil and their fractions, other than crude, whether or not refined, but not chemically modified | 2023 | 1 | 10 | -0.5075 | 19.40% | 28.32% | hazard |
| 420310 | Apparel: articles of apparel, of leather or of composition leather | 2023 | 1 | 10 | -0.5428 | 19.40% | 28.32% | hazard |
| 190230 | Food preparations: pasta (excluding stuffed), cooked or otherwise prepared | 2023 | 1 | 10 | -0.9631 | 19.40% | 28.32% | hazard |
| 030490 | Fish: fish meat n.e.s. in heading no. 0304 (whether or not minced), fresh, chilled or frozen | 2023 | 1 | 10 | -1.0137 | 19.40% | 28.32% | hazard |
| 080930 | Fruit, edible: peaches including nectarines, fresh | 2023 | 1 | 10 | -1.1183 | 19.40% | 28.32% | hazard |
| 890200 | Fishing vessels, factory ships and other vessels: for processing or preserving fishery products | 2023 | 1 | 10 | -1.2638 | 19.40% | 28.32% | hazard |
| 610190 | Coats: men's or boys' overcoats, car-coats, capes, anoraks, wind-jackets and similar articles, of textile materials n.e.s. in heading no. 6101, knitted or crocheted (excluding those of heading no. 6103) | 2023 | 1 | 10 | -1.3318 |
Most dormant capabilities, and most expected re-entries next year
| Reporter | Dormant | Median gap | Held 2024 |
|---|---|---|---|
| Cyprus | 2,635 | 12 | 397 |
| Korea, DPR | 2,626 | 13 | 197 |
| Andorra | 2,576 | 10.5 | 255 |
| Dominica | 2,203 | 12 | 231 |
| Antigua and Barbuda | 2,169 | 12 | 210 |
| Georgia | 2,141 | 13 | 391 |
| Hong Kong SAR | 2,118 | 7 | 732 |
| Lithuania | 2,101 | 8 | 1,031 |
| Reporter | Expected | Dormant | Median gap |
|---|---|---|---|
| Lithuania | 170.5 | 2,101 | 8 |
| Spain | 159.2 | 1,645 | 7 |
| Hong Kong SAR | 158.5 | 2,118 | 7 |
| Bulgaria | 154.3 | 1,976 | 9 |
| Estonia | 149.8 | 2,096 | 10 |
| Slovenia | 149.7 | 2,007 | 8 |
| Portugal | 145.0 | 1,610 | 9 |
| Latvia | 144.1 | 2,002 | 9 |
| United Kingdom | 133.2 | 1,782 | 10 |
| France | 133.1 | 1,554 | 11 |
The strongest objection to this page
Sunk-cost export hysteresis is one of the most established results in the field. Roberts and Tybout, Das, Roberts and Tybout, and Besedes and Prusa on duration and re-entry all show that prior experience raises re-entry probability, with the advantage decaying in time out of the market. Prior experience raising re-entry probability, with the advantage decaying in time out, is the lift restated. There is no new fact in the first half of this page.
The genuinely new half, the power law beating the exponential, is undermined by the fact that a mixture of heterogeneous exponentials produces a power law almost mechanically. Without disaggregated fits, a pooled power-law exponent is evidence of heterogeneity, not of a retention law.
The priority claim is conceded in the lede rather than left for a referee, and the citations are on the page. Nothing here is presented as the discovery that trade has memory.
The contribution is narrowed to two things the hysteresis literature does not provide. First, a density-matched lift on the full 233 by 4,615 panel: 3.78 to 4.68 depending on whether time is stratified alongside density, computed inside product space rather than against an unconditional base rate, and swept over strata count, RCA cutoff, cell universe and minimum gap (four figures above). Second, a fitted functional form with its horse race published in both directions, including the direction that loses.
On the mixture objection, the disaggregated fits were made a precondition of publication rather than future work, and they are the declared kill condition at the top of this page. On the raw hazard the exponent survived: positive in every one of the 21 sections, the 10 density deciles and the 228 countries, with the power law winning 21 of 21, 10 of 10 and 211 of 228 respectively, and the country median exponent 0.7976 against a pooled 0.8153. On the excess hazard it did not, so that claim is withdrawn on the page rather than defended in a footnote.
What remains unanswered: nothing here is causal, and the page does not call it causal. There are no country or product fixed effects, so the contrast is between cells that differ in their history and in everything correlated with their history. It is a well-controlled descriptive contrast, which is what it is labelled.
Method and limits
- Presence is RCA at or above 1.0 in data/parquet/rca_matrix, which stores a row only where RCA is at least 0.01. Absence in this panel therefore means "below 0.01, including no exports at all" whenever no row exists, which is how the band ladder labels it.
- The vintage is CEPII BACI 202501 (retrieved 2026-04-28) on the HS 1996 revision, which is what rca_matrix is built from. It is not HS92; the site's separate HS92 tree at data/baci_hs92 is not used here.
- The panel unit is the BACI country_code, which is what the 233 refers to. BEL, DEU and SDN carry duplicate ISO3 codes across legacy and current reporter codes; the legacy codes contribute to the pooled panel and to the country fits, and are excluded from the 2024 country layer because they do not report in 2024.
- Independent cross-checks: the pooled panel counts were re-derived in pure SQL from rca_matrix and products.parquet and matched the pipeline to the unit (4,880,148 lapsed, 340,188 re-entries, 23,628,298 virgin, 296,445 first entries, ratio 5.5562). Density for Afghanistan in 2024 was re-derived in SQL by mirroring the proximity upper triangle and applying the Hidalgo et al. (2007) definition, matching to eight decimals on three test products.
- Build time about 4 minutes, emitting 16 flat tables read directly by this page. No computation on this page beyond formatting.