assembly-economics/models/ParameterGrounding.md

Parameter Grounding Register

Status: v0.1. Most GADM parameters are still assumptions. This register says which ones have evidence behind them, which are bracketed by sensitivity analysis only, and which are open.

Status codes: G grounded in external evidence · B bracketed: not grounded, but key readings checked across a range · A assumed, not yet checked · C calibration choice (set to reproduce a target behaviour).

Parameter	Meaning	Value	Status	Basis
time unit	one period	1 year	C	WP-0005-T01; implied timescales checked in GADM-0.2.md § 3.4
dO	depreciation of organism capability	0.20 (range 0.15–0.35) per year; GADM-0.2/0.3: 0.06	G	Software depreciates geometrically over roughly 3–10 years (CBO-based summary); business R&D capital depreciation is generally above the traditional 15 % (Li & Hall 2020, Review of Income and Wealth 66(1)); economic life of AI GPUs is about 2–6 years. Organism capability combines all three.
aO, ell, oseed	organism investment, learning with use, seeding	0.50, 0.83, 0.033 (×3.33)	C	Rescaled with dO so the baseline organism path stays as before (0.46 at t = 25, 0.37 at t = 100). The level of organism capability is therefore still ungrounded.
aext	attention extraction	0.275; GADM-0.2: 0.12	G (order of magnitude)	ATUS 2023: 5.2 h/day leisure, 2.7 h TV; social media about 2 h 20 min/day. Engagement media take about half of discretionary time (GADM-0.3.md § 4.1).
r_k	channel self-reinforcement	0.3 (0.4 discovery)	B	Not grounded. Readings checked for 0.15–0.45 (results/robustness.md).
k_w	wealth → control conversion	0.04	B	Not grounded. Readings checked for 0.02–0.20.
birth, ageing and death rates	demography	1/45; 1/20, 1/45, 1/15; 1/8	C	Gives a stationary structure of about 23 / 51 / 17 / 9 % at replacement fertility, plausible for an aged high-income society.
hform	durable capability formation	0.15	C	Chosen so children's durable capability settles near 0.6.
v0, aK, n1	experimentation, capacity build, entry	2.5, 0.35, 0.30	C	Keep the GADM-0.2 baseline from collapsing (GADM-0.2.md § 3.4).
all other rates	—	see code	A	First guesses in the 0.03–0.3 per-year range.

Robustness of key readings (T02)

simulations/gadm02/results/robustness.md, GADM-0.4 with cohorts and durable capability. Channel counters are recalibrated for every variant.

Reading	dO 0.06 → 0.20	r 0.15 / 0.45	k_w 0.02 / 0.20
Generative regime best, automated capitalism worst	holds	holds	holds
Scenario ranking (Spearman ρ vs. grounded)	1.00	0.98 / 1.00	1.00 / 1.00
Generative regime has the lowest domination	holds	holds	holds
Organism lever order lineage > membrane > attention	holds	holds	holds
P3: full wealth tax lowers P by < 0.06 where membrane/lineage dominate	holds (−0.055)	holds (−0.035) / fails (−0.078)	holds

Readings:

1. Grounding dO changes almost nothing, because the organism level was held fixed by rescaling. The GADM-0.2 Sobol result ("dO explains a third of baseline variance") really measures sensitivity to the level of organism capability, which dO sets together with investment and learning. That level is the next thing to ground, for example from AI-capital or task-automation shares.
2. The structural readings are robust across the brackets for the two ungrounded power parameters.
3. P3 is robust in direction, but its size depends on r. With strong self-reinforcement, market and political channels sit closer to their tipping points, so a wealth tax tips them down and becomes more effective (ΔP −0.078). Even then, total domination stays dominated by membrane and lineage control.

Open grounding needs

1. The level of organism capability K_Ω (AI capital share, task-automation share).
2. The channel self-reinforcement r_k (persistence of market leadership, platform tipping evidence).
3. The wealth → influence conversion k_w (political-economy evidence on lobbying and influence).
4. Durable capability formation hform and the ½ / ½ durable/current split (human-capital literature on the persistence of early education).

Sources

• Li, W. C. Y. & Hall, B. H. (2020). Depreciation of Business R&D Capital. Review of Income and Wealth 66(1): 161–180. https://www.bea.gov/research/papers/2016/depreciation-business-rd-capital
• BEA, Estimation of Software in the US National Accounts. https://www.bea.gov/sites/default/files/2018-05/Estimation-of-Software-in-the-US-National-Accounts.pdf
• Software depreciation schedule (CBO-based summary). https://www.route-fifty.com/digital-government/2002/05/by-the-numbers/286193/
• AI GPU economic life: https://siliconangle.com/2025/11/22/resetting-gpu-depreciation-ai-factories-bend-dont-break-useful-life-assumptions/ ; https://drops.mts.now/ai-capex/wiki/economics/gpu-depreciation/
• BLS American Time Use Survey. https://www.bls.gov/news.release/PDF/atus.pdf