Iterative Missing Data Imputation with Model Form Adaptation and Non-Missing Feature Supervision

Iterative imputation is a prevalent method for missing data imputation, where each feature is imputed iteratively by treating it as a target variable estimated from all other features. However, iterative imputation method suffers from two principal limitations: ❶ it imposes a single parametric model form to impute all features , neglecting the potential for optimal models to vary among features, which risks model misspecification; and ❷ it assumes every feature contains missing values , overlooking the potential presence of non-missing features, termed as oracle features , which are informative for imputation. To address these limitations, we propose kernel point imputation (KPI), a bi-level optimization framework for iterative missing data imputation. At the inner level, KPI adaptively learns the optimal model form for each feature within a reproducing kernel Hilbert space, addressing limitation ❶ . At the outer level, KPI utilizes oracle features as supervisory signals to iteratively refine the imputations, addressing limitation ❷ . Experiments demonstrate that KPI outperforms competitive imputation methods. Code is available at https://github.com/FMLYD/kpi.git .