Batch cycle-001. Model 0.1.0, graph 0.2.0, parameters 0.1.0. 100 simulations, seeds 1 to 100; probes on 20. Every figure is a distribution over simulations of a structural model with seed parameter values; it shows what the model implies under these settings, not what will happen. Other nations are frozen at their 2026 ratings. No reconstructed historical data is used in this experiment.
Headline
United Kingdom played 20 rounds from 2026 under the random method, with stochastic events, 100 times. Its capability index moved from 16.45 to a median of 17.38 (+0.93), with 90 per cent of simulations between 16.36 and 18.24 [experiment_objectives].
Starting position
In 2026 the nation ranks 3 on the index against the frozen field, holds 2 of nine domains at Tier 1 and has a tier rank of 5. Its base income is 951 credits a year, calibrated so that its 2026 position is affordable with headroom for investment.
What was decided
A simulation spent a median of 2,523 credits on moves. The five groups that took most were Space Operations (partner, 41 credits, 0.6 per cent); Labour & Employment (build, 41 credits, 0.6 per cent); Sovereign Capital & External Financial Power (build, 41 credits, 0.6 per cent); Energy Infrastructure (partner, 40 credits, 0.5 per cent); Joint Command, Projection & Sustainment (build, 39 credits, 0.7 per cent) [experiment_decisions_by_group]. By mode: build 36 per cent, partner 36 per cent, buy 27 per cent [experiment_decisions_by_group]. Concentration of spending (HHI) had a median of 0.028, and the most repeated action appeared in 15 per cent of rounds.
The leading domain by period: rounds 1 to 5, National Security; rounds 6 to 10, Strategic Infrastructure; rounds 11 to 15, Critical Technology; rounds 16 to 20, Critical Technology [experiment_spend_by_period].
What the world did
A median simulation saw 2 shocks and 1 upside events. The most damaging per firing were S01 (26 firings in 22 simulations, −24.4 points each); S08 (33 firings in 29 simulations, −23.7 points each); S03 (33 firings in 31 simulations, −23.5 points each) [experiment_shocks]. Upside events fired 143 times across all simulations [experiment_shocks].
The groups that lost most to shocks, per simulation: Fiscal Capacity & Public Finance −1.03; Economic Leverage & Dependence −1.00; Trade Facilitation & Logistics −0.94; Digital & Services Trade −0.89 [experiment_shock_damage_by_group].
The edges that carried most change through the graph, per simulation: Economic Output & Productivity to Fiscal Capacity & Public Finance (+0.16 points); Fiscal Capacity & Public Finance to Social Infrastructure (0.00 points); Semiconductors & Advanced Computing to Artificial Intelligence (+0.11 points) [experiment_propagation_by_edge].
Where it ended
At 2046 the median rank is 2 (5th to 95th percentile 1 to 4), the median count of Tier 1 domains 7 (3 to 7) and the median tier rank 2; the resilient score, the mean score sum over simulations, is 1,263 [experiment_objectives].
Tier 1 probability changed most in: financial strength (0 to 78 per cent of simulations); human capital (0 to 99 per cent of simulations); information and influence (0 to 79 per cent of simulations); production and innovation (100 to 83 per cent of simulations); strategic infrastructure (0 to 73 per cent of simulations) [experiment_tiers_by_round].
Why
Without shocks the index ends +0.742 higher on average, so the shocks cost about 0.742 index points [experiment_probe_attribution].
Holding instead of following this method changes the index by −1.215: that is the method's worth against doing nothing [experiment_probe_attribution].
Removing any single one of the five largest actions changes the index by between −0.024 and −0.013, for example 2039 build Strategic Strike & Missile Defence (48 credits) [experiment_probe_attribution]. The largest actions by credits come late, when income is highest, and are rarely the most valuable.
Removing the largest shock of a simulation raises the index by +0.351 on average [experiment_probe_attribution].
The replay probe reproduces the simulations exactly (index change 0.000000), so the attributions are clean [experiment_probe_attribution].
Surprises
move_without_shock (warn): largest one-year move in a group with no shock landing: 3.18 points; 3% of simulations have one above 3.
tier_jump (warn): largest gain in one domain within five years: 4 tiers (4 simulations above 2).
saturation_high (warn): 65% of simulations end with a group at 20 that did not start there (median 1 groups).
retired_words (warn): e3-gbr-random/report.md: 'simulations' 3 time(s), first near line 39; use 'simulations'.
The simulation furthest from the median (seed 33) ends −2.09 from it, with 7 shocks and 0 upside events [experiment_outlier_simulations].
Comparison
Against the hold experiment for the same nation (e3-gbr-hold), the median index is +1.24 points apart, the median rank 2 against 5, and Tier 1 domains 7 against 1 [experiment_against_hold].
No backcast comparison: this experiment does not start from a historical position [experiment_against_history].