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Victor K. de la Pena

Publications and source records attributed to Victor K. de la Pena.

2 recordsLinked to original sources

Mitigating the Winner's Curse While Controlling Multiplicity: e-Process Methods for Anytime-Valid Inference in Dose-Ranging Trials

Phase II dose-ranging trials often report the largest observed dose-control effect while inspecting accumulating data repeatedly. This creates two coupled distortions: selection optimism from choosing the empirical winner, known as the winner's curse, and Type I error inflation from multiplicity across doses and interim looks. We develop an anytime-valid procedure for testing whether the best true dose effect exceeds a clinically meaningful margin. The mathematical starting point is a recent selection-premium identity for the running maximum: for dose-control scores, the expected gain from re-selecting the current leader becomes a predictable selection charge. Subtracting this charge gives a residual with nonpositive drift under the composite null; applying a one-sided mixture-exponential construction then yields an e-process and hence an anytime-valid global test. The resulting rule has a transparent ledger form: raw best effect minus selection charge minus monitoring margin, and a ``GO'' decision is made only when the remaining evidence still exceeds the clinical margin. We give plug-in implementations for Gaussian and binary outcomes, prove finite-sample Type I control and anytime lower confidence bounds for the best dose effect, and illustrate the method through a worked example and simulations.

stat.ME↗

A Selection Premium Decomposition for the Expected Maximum of Random Walks

When $K$ models are evaluated on the same validation set of size $n$, the selected winner's apparent performance is biased upward. Suppose $K$ models are evaluated on a shared sequence of i.i.d. observations $X_1,\dots, X_n$, where model $k$ achieves response $f_k(X_i)$ with mean $μ_k = \mathbb E[f_k(X)]$. Writing $Y_{i,k} = f_k(X_i)-μ_k$ for the centered increment and $S_{n,k} = \sum_{i=1}^n Y_{i,k}$ for the centered cumulative score, the expected maximum satisfies $0\le\mathbb E\bigl[\max_k S_{n,k}\bigr] = \sum_{i=1}^n \mathbb E\bigl[φ_K(S_{i-1})\bigr]$ where $φ_K(u) = \mathbb{E}\bigl[\max_k(u_k + Y_k)\bigr] - \max_k u_k$, $u\in \mathbb R^K$, is the selection premium function. This formula corresponds to the null hypothesis case (all models are equal in the sense that they have the same mean), which clarifies that the bias arises from selection. While this decomposition follows from elementary conditioning and telescoping, we develop the analytical consequences in five directions. (i) structural properties of $φ_K$; (ii) extension to stopping times, recovering Wald's equation at $K=1$; (iii) a winner's curse decomposition for heterogeneous means; (iv) a universal bias concentration law showing that the first $α$-fraction of observations generates a $\sqrtα$-fraction of total bias.

math.ST↗