{
  "id": 13044329,
  "title": "When Does a Pathway Score Preserve a Mediated Effect? Aggregation Geometry, Minimax Adequacy, and Gap Inference for High-Dimensional Mediation",
  "url": "https://urgent.news/2026/10/08/when-does-a-pathway-score-preserve-a-mediated-effect-aggregation",
  "topic": "science",
  "section": "Science",
  "published": "2026-10-08T00:00:00.000Z",
  "source": {
    "name": "bioRxiv",
    "slug": "biorxiv",
    "url": "https://www.biorxiv.org/content/10.64898/2026.10.02.756279v1?rss=1"
  },
  "original_language": "en",
  "account": "When collapsing high-dimensional mediators into low-dimensional scores for mediation analysis, maintaining the full mediated effect is crucial. The study investigates when a linear score preserves this effect. Exact preservation occurs when the score includes the covariance-adjusted exposure-predictive mediator direction, which serves as the classical sufficient reduction for exposure under a Gaussian inverse-regression model.\n\nThe researchers introduce a distribution-free minimax adequacy loss, calculated as the fraction of exposure-relevant mediator information lost by the score. This loss is directly related to the overlap recovered through aggregation. To ensure unbiased estimators of retained and full exposure information, a split-sample inverse-Wishart correction is proposed, providing accurate results in moderate dimensions.\n\nUnder spherically symmetric outcome-effect benchmarks, the relative aggregation error follows a Cauchy location-scale profile. For paired influence-function inference, the realized gap between retained and comprehensive exposure information is targeted. Simulations show that paired interval coverage ranges from 93.3% to 97.5%. In an outcome-free analysis of 1,314 smoking-responsive genes from a lung adenocarcinoma audit, retaining promoter and non-promoter means separately reduces pooled loss compared to a dimension-only random-subspace benchmark. Independent half-sample screening proves unstable, but top-100 and top-250 cross-screen pooled gene-mean losses range from 0.827 to 0.932. The framework distinguishes structural adequacy, benchmark fragility, and outcome-specific discrepancy.",
  "summary": "High-dimensional mediators are routinely collapsed into low-dimensional scores before mediation analysis, but aggregation can change the mediated estimand rather than merely reduce noise. We characterize when a linear score preserves the full mediated effect. Exact preservation for every outcome model occurs precisely when the score contains the covariance-adjusted exposure-predictive mediator…",
  "key_points": [],
  "editors_take": null,
  "illustration": null,
  "coverage": {
    "outlets": 1,
    "also_reported_by": []
  },
  "ai_generated": true,
  "disclaimer": "Summaries, key points and the editor’s take are written by software from other outlets’ reporting and may contain errors — always check the linked original."
}