Source
https://sophiajwang.com/projects/ssi/Self%20Sufficiency%20Index%20SSI%20v0%20Sophia%20Wang.pdf — original source (opens in a new tab; the file is not redistributed)
Wang (2025) — Self-Sufficiency Index (SSI)
The primary source of the model's composite SSI = ∛(SL × QL × Sustainability)
Sophia Wang’s working paper (Feb 2025) defining a multi-domain composite Self-Sufficiency Index for villages — the actual primary behind the NI Tier-2 composite (
X1_Composite). Confirms the geometric-mean composite and the self-sufficiency ratio (local production ÷ demand), and reveals an import/export distance-weighting and domain priority weights the model does not yet implement. v0/early-stage, rural-India context → data_quality: medium.
Summary
A 16-page working paper (Sophia Wang, February 2025) proposing a multi-domain composite Self-Sufficiency Index (SSI) for villages, motivated by rural-India self-reliance (Gandhi; the Mandede/Pabal villages; Vigyan Ashram). It defines SSI as the geometric mean of three normalised dimensions — Standard of Living (SL), Quality of Life (QL), and Sustainability (S) — with SL built from per-domain self-sufficiency ratios (local production ÷ demand) plus distance-biased import/export adjustments. For Neobiome it is the methodological taproot: the NI Tier-2 composite is Wang’s SSI geometric mean applied to the SL layer (Energy/Water/Food). Early-stage (“v0”), unpublished; several normalisation schemes are explicitly flagged incomplete.
Key claims
- claim: "SSI = cube-root(SL × QL × Sustainability) — the geometric mean of three [0,1]-normalised dimensions: Standard of Living (SL), Quality of Life (QL), and Sustainability (S). Village-scale, bottom-up; the geometric mean is chosen to capture compounded effects, as in the UNDP Human Development Index. This is the composite the NI Tier-2 SSI (X1_Composite) implements, applied to the SL layer."
source_location: "§1 Index General Form, eq (1)"
- claim: "SL (Standard of Living) = Σ_x γ_priority^x [ (local_production/demand) − γ_d,M·(remaining_demand/demand) + γ_d,X·(excess_production/demand) ]. The core term is the per-domain SELF-SUFFICIENCY RATIO (local production ÷ demand) — explicitly NOT production ÷ production-potential, so as to acknowledge the diminishing/adverse returns of excess production. SL domains: Nutrition (kcal/day), Water (L/day), Energy (kWh/day), Waste Management (kg/day), Income, Housing, Health, Education; domain priority weights γ_priority sum to 1."
source_location: "§1.1 Standard of Living, eq (2) + Table 1"
- claim: "Import/export DISTANCE weighting: imports are penalised with distance (γ_d,M = 0.2 for ≤10 km, 0.5 for 10–50, 0.7 for 50–100, 1.0 for >100 km) and exports are rewarded for being local (γ_d,X = 1.0 for ≤10 km, 0.7 for 10–50, 0.5 for 50–100, 0.2 for >100 km) — encouraging local sourcing and nearby exports. The per-domain SL term falls in [−1, 2] and is rescaled to [0,1] either linearly (SL/3 + 1/3) or by percentile across many villages."
source_location: "§1.1, eqs (3)(4) + Linear/Percentile scaling"
- claim: "QL (Quality of Life) follows Bhutan's Gross National Happiness (GNH = H^H + H^U·A_suff^U), with 9 threshold-based domains aggregated by an unweighted arithmetic mean. Sustainability (S) is the mean (arithmetic, possibly geometric) of six indicators: ΔGrowth (R-squared goodness-of-fit of SSI over the previous 5–10 years), Short/Long-Term Investments, Cooperation & Dependencies, Adaptability to Modernization (Technology), Capacity for Innovation, and Natural Capital."
source_location: "§1.2 QL (eq 5, Table 2) + §1.3 Sustainability (eqs 6–18)"
- claim: "Framing: 'no village can be entirely self-sufficient … the distinction between self-sufficiency and isolation is in its scale of dependencies, and not the altogether lack of dependencies' — self-sufficiency is explicitly NOT autarky/isolation. The index is an early-stage ('v0') formulation; normalisation schemes for several SL service domains and S indicators are flagged as open questions."
source_location: "§1.3.3 Cooperation & Dependencies; Introduction; §1.1 open questions"Neobiome Intelligence relevance
This is the methodological taproot of the NI composite. The model’s Tier-2 composite (X1_Composite) is exactly Wang’s SSI = ∛(SL × QL × S) applied to the SL layer (Energy/Water/Food), so this primary confirms three core design choices: the geometric-mean composite (non-substitutable domains), the per-domain self-sufficiency ratio = local production ÷ demand, and demand (not production-potential) as the denominator — all matching the build. It also surfaces two enhancements the model does not yet implement, both well-motivated: (1) import/export distance-weighting — credit production more when imports would have to travel far and exports stay local (a “localness” reward the NI SL layer could add); and (2) domain priority weights (γ_priority, Σ=1) — the NI model currently uses equal weights as levers, but Wang’s framework supports explicit prioritisation. It confirms the model’s deliberate SL-layer-only scope: QL (a Gross-National-Happiness-style survey layer) and S (a 6-indicator sustainability layer, including an R² growth-trend term) are qualitative/data-heavy and out of NI scope — consistent with model_design.md (“SL layer only — NOT the full Wang SSI”). The framing that self-sufficiency ≠ isolation (it is the scale of dependencies, not their absence) is a useful thesis anchor. Resolves RT_016. ⚠ v0/unpublished, rural-India motivation — the formula structure is authoritative for our use, but the broader index (QL, S, several normalisations) is incomplete and should not be cited as settled.
Research targets
Research gaps
- RT_016 (RESOLVED → this page): the Wang SSI primary is now held; the composite formula + SL self-sufficiency ratio are sourced.
- Documented model enhancement (no RT — captured here + on the concept page): evaluate adding (a) import/export distance-weighting and (b) domain priority weights to the NI SL layer, per Wang eqs (2)–(4).
Connections
Referenced by
Concepts (1): Self-Sufficiency Calculation Framework