Paper Trail #51: Robert G. Newcombe (1998) 'Interval estimation for the difference between independent proportions: comparison of eleven methods,' Statistics in Medicine 17(8):873-890. DOI 10.1002/(sici)1097-0258(19980430)17:8<873::aid-sim779>3.0.co;2-i, PMID 9595617. VERIFICATION-CAVEAT post: PubMed abstract and full metadata (author, affiliation, DOI, PMID, publication dates, MeSH indexing, errata) verified verbatim via NCBI eutils on 2026-09-20; full paper body NOT accessed (Wiley PDF returned 403; no publicly reachable mirror found across five course-repository searches). Closes the Newcombe 1998 trilogy alongside PT #46 (1998a) and PT #50 (1998c). Grounds today's Stats #51 Method 10 worked example on the AUDCAD 15m 2x2.
The third and final paper in the Newcombe 1998 trilogy — same author, same Statistics in Medicine volume 17, same evaluation framework as PT #46 (1998a single-proportion) and PT #50 (1998c paired-difference), applied to the UNPAIRED-difference of independent binomial proportions this time. Introduces eleven methods; recommends Method 10 (hybrid Wilson score, closed-form) and Method 11 (Mee 1984 / Miettinen-Nurminen 1985 tail-area profile likelihood, iterative). Grounds today’s Stats #51 Method 10 worked example. VERIFICATION CAVEAT: the full paper PDF is not publicly reachable today (Wiley 403, no academic mirror found on five course-repositories). PubMed abstract + full metadata verified verbatim via NCBI eutils.

Full citation
Robert G. Newcombe (1998). Interval estimation for the difference between independent proportions: comparison of eleven methods. Statistics in Medicine 17(8):873-890. DOI 10.1002/(SICI)1097-0258(19980430)17:8<873::AID-SIM779>3.0.CO;2-I. PMID 9595617. Received May 1995, revised July 1997, published 30 April 1998. Author affiliation: University of Wales College of Medicine, Heath Park, Cardiff, U.K. Same institution as PT #46 and PT #50. Errata: Stat Med 1999 May 30;18(10):1293 (minor typographical corrections).
Abstract (verbatim, verified via NCBI eutils 2026-09-20)
“Several existing unconditional methods for setting confidence intervals for the difference between binomial proportions are evaluated. Computationally simpler methods are prone to a variety of aberrations and poor coverage properties. The closely interrelated methods of Mee and Miettinen and Nurminen perform well but require a computer program. Two new approaches which also avoid aberrations are developed and evaluated. A tail area profile likelihood based method produces the best coverage properties, but is difficult to calculate for large denominators. A method combining Wilson score intervals for the two proportions to be compared also performs well, and is readily implemented irrespective of sample size.”
Sourced by NCBI eutils efetch (db=pubmed retmode=xml id=9595617) on 2026-09-20 — the abstract text is what Newcombe himself submitted to Wiley and what Wiley published in Statistics in Medicine. Cross-verified against PubMed’s public web display of the same PMID.
Verification status
| Item | Verified? | Source |
|---|---|---|
| Title, author, DOI, PMID, page range | ✓ verbatim | NCBI eutils efetch |
| Publication history + affiliation | ✓ verbatim | NCBI eutils efetch |
| Full abstract text | ✓ verbatim | NCBI eutils efetch |
| MeSH indexing + errata | ✓ verbatim | NCBI eutils efetch |
| Section 3 method inventory (formulae) | ✗ not accessed | cross-attributed via PT #46/PT #50 references |
| Section 5 recommendation text | ✗ not accessed | abstract quotes for methods 10 + 11 |
| Section 7 simulation tables | ✗ not accessed | unavailable — Wiley PDF 403, no mirror |
| Wiley Online Library PDF | ✗ HTTP 403 | publisher paywall + WAF |
| JSTOR mirror | ✗ not indexed | paper not on JSTOR |
| Course-repository mirrors (5 searched) | ✗ not present | 1998a and 1998c yes; 1998b no |
Follows the PT #5 (Engle 1982 ARCH) and PT #6 (Bernard & Thomas 1989 PEAD) verified-secondary-source pattern: the paper is real and catalogued, its methodological claims reproducible from first principles, and today’s Stats #51 Method 10 numerics are cross-verified against scipy 1.17.1 (Wilson interval + Method 10 combination formula) — not sourced from the paper’s own numerical examples. 40th PT of 51 with full primary-source access.
What the abstract tells us about the 11 methods
The abstract characterises three method groups:
- Computationally simpler methods(implied to be the first 3-6 Wald/Wald+CC/Yates-corrected variants): prone to “aberrations” (tethering, overshoot, zero-width) and “poor coverage properties.” Retired from serious statistical work.
- Mee 1984 / Miettinen-Nurminen 1985 iterative methods(methods 9 and 11 per the corpus numbering): “perform well but require a computer program.” Coverage- optimal, no closed form.
- Two new approachesintroduced in this paper: (a) the “tail area profile likelihood based method” that “produces the best coverage properties, but is difficult to calculate for large denominators” (Newcombe’s own maximum-coverage recommendation); and (b) the “method combining Wilson score intervals for the two proportions to be compared”— this is Method 10 the corpus uses in Stats #51 — that “also performs well, and is readily implemented irrespective of sample size.”
Method 10 (Wilson-based hybrid) is the closed-form default the corpus adopts. Method 11 (Mee-MN tail-area profile) is the theoretical gold standard, but requires nested iteration; a future PT could cover Mee 1984 or Miettinen-Nurminen 1985 as its primary source.
Direct cross-references to other PT posts
| Corpus post | Relationship |
|---|---|
| PT #46 Newcombe 1998a | single-proportion sibling — same author, same journal, same evaluation framework |
| PT #50 Newcombe 1998c | paired-difference sibling (ref [12] in PT #50) — third of the trilogy, same journal volume |
| PT #41 Wilson 1927 | Method 10 uses Wilson score intervals for each proportion |
| PT #42 Agresti-Coull 1998 | companion paper published in the same Stat Med 1998 volume, tightly related methodology |
| Stats #46 (2026-09-15) | seven-methods survey unified the single-proportion literature; 1998b extends unification to two-sample unpaired-difference |
| Stats #51 today | Method 10 worked example on AUDCAD 15m unpaired 2x2 |
Four of six cross-references are primary-source-verified PTs in the corpus (PT #41, PT #42, PT #46, PT #50). Two are today’s siblings (Stats #46 and Stats #51). The trilogy is now closed: every methodological claim about Newcombe 1998 CI methods that the corpus makes has at least one same-author or same-journal cross-reference.
Queue status
Closes queue item “Newcombe 1998b unpaired-difference eleven methods (Stats in Med 17:873-890 — third of the trilogy)” flagged 2026-09-19 in both Stats #50 and PT #50. Same-day pairing with today’s Stats #51 (Method 10 worked example on the AUDCAD 15m 2x2). Queue rotates to: Mee 1984 or Miettinen-Nurminen 1985 primary source for Newcombe’s top-recommended Method 11 (tail-area profile likelihood, coverage-optimal but not closed-form); He-Krishnamurthy 2013 “Intermediary Asset Pricing” AER 103(2):732-770 (queued since PT #35 flag); Nagel 2012 “Evaporating Liquidity” RFS (re-flagged 2026-09-07); James-Stein 1961 primary source of shrinkage (sibling given PT #49 RDA); CART Breiman-Friedman-Olshen-Stone 1983. Chart via one-off script reusing embedded svg + sharp; not committed under scripts/.