feat(psychometric): restore Driver p.16 TIPREDVARstd v/v=1 on main

[seonghobae]

Restore one named Driver, Oud, and Voelkle (2017) p. 16 map on current main: scalar TIPREDVARstd as v / v = 1 after strictly positive TIPREDVAR.

Paper (re-opened this cycle)

JSS PDF re-opened 2026-09-01T19:20Z from https://www.jstatsoft.org/index.php/jss/article/download/v077i05/1104.

• Table 3, p. 13 names TIPREDVAR the lower-triangular n.TIpred × n.TIpred Cholesky matrix of time-independent predictors variance/covariance.
• Table 2, p. 12 does not name TIPREDVAR.
• p. 16 prints standardised matrices with the suffix std when appropriate. The printed example is discreteDRIFTstd, not TIPREDVARstd.
• Footnote 4: standardisations use only the relevant variance, not the total.

2017-era cran/ctsem 2.5.0 R/summary.ctsemFit.R (re-opened this cycle):

if(verbose==TRUE){
  TIPREDVARdiag<-tryCatch({diag(diag(TIPREDVAR),n.TIpred)+diag(c(ridging),n.TIpred)}, error=function(e) e )
  TIPREDVARstd<-tryCatch({suppressWarnings(solve(sqrt(TIPREDVARdiag)) %&% TIPREDVAR)}, error=function(e) e )
  tryCatch({  dimnames(TIPREDVARstd)<-list(TIpredNames,TIpredNames)}, error=function(e) e )

if(ridging==TRUE) ridging<- .0001 else ridging <- 0. Default ridge is 0. Unlike TRAITVAR / MANIFESTTRAITVAR, that source does not skip forming TIPREDVARstd when v = 0; solve(sqrt(0)) fails. OpenMx %&% is t(A) %*% B %*% A.

Meredith (1993) remains unread. Mislevy (1991) remains unread.

Map

recover_standardised_time_independent_predictor_variance:

1. Event clock only.
2. Finite, non-negative v.
3. Zero v fails closed (StandardisedTimeIndependentPredictorVarianceRequiresPositivePredictorVariance).
4. Form 1 / √v, then (1 / √v) v (1 / √v). Return the quadratic form, not a hardcoded Ok(1.0).
5. Distinct positive v recover the same 1.
6. TIPREDVAR does not require stable a < 0.

Refuses (equal numbers remain distinct named quantities):

• unstandardised TIPREDVAR is not TIPREDVARstd
• MANIFESTVARstd θ / θ = 1 is not TIPREDVARstd (this crate already exports MANIFESTVARstd)
• §7.2 addedTIPREDVAR (B / a)² v is extra process variance, not this correlation

The existing refuse of TIPREDVARstd as asymDIFFUSIONstd is kept.

Not this PR

• Does not convert stale draft feat(psychometric): restore Driver p.16 TIPREDVARstd v/v=1 on main #272 / feat(psychometric): restore Driver p.16 TIPREDVARstd v/v=1 on main #315.
• Does not restore DIFFUSIONstd q / p = −2 a.
• Does not merge. Author will not self-approve.
• Independent non-author APPROVE plus exact-head required-check success is still required before squash-merge.

Local verification

• cargo +1.98.0 test -p psychometric_core --lib — 189 passed
• focused TIPREDVARstd integration tests — passed
• cargo +1.98.0 clippy -p psychometric_core --all-targets -- -D warnings — clean
• RUSTDOCFLAGS='-D warnings' cargo +1.98.0 doc -p psychometric_core --no-deps — clean
• cargo +1.98.0 fmt --all -- --check — clean

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📥 Commits

Reviewing files that changed from the base of the PR and between 1bc02f5 and d99d946.

📒 Files selected for processing (8)

• CHANGELOG.md
• crates/psychometric_core/src/error.rs
• crates/psychometric_core/src/event_time.rs
• crates/psychometric_core/src/lib.rs
• crates/psychometric_core/tests/multilevel_event_time_recovery_contract.rs
• crates/psychometric_core/tests/scientific_claim_boundary_contract.rs
• docs/adr/0005-posterior-esem-dsem.md
• docs/research/multilevel-event-time-recovery.md

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[devin-ai-integration]

Devin Review found 2 potential issues.

[devin-ai-integration]

🔍 Adjacent estimator docs remain merged

The recover_standardised_asymptotic_diffusion comment absorbs the following TRAITVARstd discussion. Rustdoc misattributes that contract and leaves the trait estimator undocumented.

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[devin-ai-integration]

📝 Info: Extreme inputs remain representable

The sqrt and staged scaling sequence keeps all positive finite inputs representable. Subnormal inputs can return a few ulps from mathematical one.

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[seonghobae]

Canonical-owner repair started in ContextualWisdomLab/fast-mlsirm#1721 (issue #1720). This PR's static D^{-1/2} Σ D^{-1/2} arithmetic belongs to fast-mlsirm; TEPP owns the EventTime admission/temporal adapter. The upstream PR preserves a test-first generic scalar+matrix contract and the Driver/ctsem provenance without importing TEPP clocks or names. Closing this TEPP implementation prevents duplicate production authority while preserving this branch's TIPREDVARstd fixtures/research as downstream parity evidence. TEPP should add only the EventTime ACL after a released/versioned fast-mlsirm contract exists; an open upstream PR head is not a production dependency.