greenbook 0.1.0
- Initial release. Implements Phase 1 to Phase 3 cost-benefit analysis
primitives from HM Treasury Green Book guidance.
Discounting
gb_stpr(), gb_discount_factor(),
gb_discount(): kinked Social Time Preference Rate
(standard, health, catastrophic-risk variants) and discount
factors.
gb_npv(), gb_eanc(): net present value and
equivalent annual net cost.
Real-terms rebasing
gb_deflator(), gb_real(),
gb_rebase(): GDP-deflator factors and real-terms conversion
against a bundled vintage.
Optimism bias
gb_optimism_bias(), gb_apply_ob(),
gb_categories(): lookups for the Mott MacDonald (2002)
upper bounds across six project categories with mitigation factor
support.
Distributional analysis
gb_dist_weight(), gb_dist_weighted_npv():
iso-elastic distributional weights using Green Book default eta =
1.3.
Adjustments
gb_metb(): Marginal Excess Tax Burden uplift with
vintage lookup (20 percent in 2018+, 30 percent historical).
Valuation library
gb_wellby(): WELLBY conversion to GBP per HMT Wellbeing
Guidance (July 2021). Central GBP 13,000 in 2019 prices.
gb_vpf(): Value of Preventing a Fatality per DfT TAG.
GBP 2.153 million in 2024 prices.
gb_qaly(): Quality-Adjusted Life Year per DHSC
supplementary Green Book guidance (GBP 70k) plus NICE thresholds.
Carbon
gb_carbon_value(): DESNZ Carbon Values for Appraisal,
central / low / high paths, traded and non-traded sectors.
gb_carbon_npv(): NPV of an emissions path with full
discounting and rebasing.
High-level appraisal
gb_appraise(): end-to-end appraisal in one call.
Optionally applies optimism bias and METB to costs, then computes NPV
and BCR with full provenance.
gb_compare(): side-by-side comparison of two or more
options with NPV / BCR / EANC ranking and preferred-option
selection.
gb_progression(): track an appraisal across SOC, OBC,
FBC business case stages.
gb_place_based(): aggregate sub-projects into a
place-based business case (per Green Book 2026), with optional synergy
uplift.
gb_economic_case(): wrap an appraisal in Five Case
Model Economic Case structure (CSFs, options, monetised summary,
non-monetised, VfM, recommendation).
gb_validate(): lint an appraisal for sign-convention,
base-year, schedule, and consistency errors.
Risk
gb_risk_register(): build a risk register with
monetised exposure (probability x impact), aggregate by category, and
optionally risk-adjust an appraisal NPV.
Sensitivity
gb_sensitivity_ob(): optimism bias sensitivity sweep
across a vector of mitigation factors. Required at every Green Book
business case gateway.
Reporting
gb_headline(): one-page summary with NPV, BCR, EANC,
payback, and provenance.
gb_cost_per_unit(): cost-effectiveness ratio (PV cost
per QALY, WELLBY, tCO2e, etc.).
gb_to_latex(): render an appraisal as a LaTeX
table.
gb_to_excel(): multi-sheet Excel export (requires
openxlsx).
gb_to_word(): one-page Word document export (requires
officer and flextable).
Lookups and provenance
gb_schedule_table(), gb_data_versions():
tibble of the STPR schedule and vintage metadata for all eight bundled
parameter tables (STPR, GDP deflator, optimism bias, METB, WELLBY, VPF,
QALY, carbon values).
gb_appraisal S3 class with print(),
summary(), format() methods. The
summary() method renders BCR, optimism bias, METB,
distributional eta, and unweighted NPV when present.