stratifyR 2.0-1 (2026-06-14)

New features

• strata.data() and strata.distr() gain a method argument supporting three optimisation strategies:
  • "dp" (default) — the original exhaustive Dynamic Programming grid search, guaranteed globally optimal on the discrete grid.
  • "cobyla" — multi-start gradient-free local optimiser (COBYLA) via nloptr; faster than DP for large h, suitable for exploratory work.
  • "global" — two-phase global optimiser combining DIRECT-L (deterministic space-filling search) followed by COBYLA local refinement; closest to DP accuracy among the two new methods.
• New arguments n_starts, max_iter, tol, and verbose in both functions to control COBYLA/GLOBAL behaviour.
• DESCRIPTION updated: nloptr added to Imports.

Bug fixes

• Weibull and Gamma recurrences (critical): distr.root() and data.root() were using the unregularized upper incomplete gamma function UGamma(s, z) (via zipfR) where the regularized form Q(s, z) was required by the mathematical formulation. Fixed by replacing all calls with pgamma(z, shape = s, lower.tail = FALSE), which correctly implements Q(s, z) = Γ(s, z) / Γ(s) as defined in Abramowitz & Stegun (1972), Chapter 6, equation 6.5.2. Results for Weibull and Gamma populations are now consistent with the published theory.
• Triangular fitting in .refit_real_scale(): simultaneous MLE of all three triangular parameters (min, max, mode) produced degenerate estimates (min ≈ max ≈ mode). Fixed by fixing min and max to sample bounds and estimating only the mode via MLE, matching the approach already used in get.dist().
• get.dist(): triangular distribution now only selected over a tail model (Gamma, Weibull, Log-normal, Exponential) when its AIC advantage exceeds 10 units, preventing spurious triangular wins on mildly right-skewed data.

Vignette

• New Section 6: Alternative Optimisation Methods: COBYLA and GLOBAL — describes the motivation, algorithm, advantages, and limitations of each method, with a worked comparison example using the Anaemia/Iron data.
• New Section 8: Summary of Method Comparison Across All Supported Distributions — presents a table of DP vs COBYLA vs GLOBAL results across all ten distributions with explanation of observed patterns.
• Corrected description of Q(r, y) (regularized) vs Γ(r, y) (unregularized) in the Weibull and Gamma sections, with explicit R implementation note.
• Fixed incorrect Normal distribution example (wrong mean/sd parameters).
• Updated triangular parameter estimation example to use the fixed fix.arg approach.
• Minor fixes: removed duplicate NeedsCompilation field, removed stray \url{} in Introduction.

Backward compatibility

• All strata.data() / strata.distr() call signatures from v1.0-5 work without modification (method defaults to "dp").
• The "strata" S3 class and all slot names are unchanged.

stratifyR 1.0-5 (2026-06-04)

Initial CRAN-submission-ready version. Implemented DP solver, 10-family distribution fitting via AIC, Neyman allocation with cost support, and coloured summary.strata() output.