Deep semi-supervised regression via pseudo-label filtering and calibration

Semi-supervised learning (SSL) is a widely used model training paradigm that effectively utilizes a limited set of labeled data and a substantially larger pool of unlabeled data. Historically, the focus of SSL research has predominantly been on classification tasks, employing methods such as consistency regularization and pseudo-labeling. However, the direct application of these methods to regression tasks presents significant challenges, primarily due to the complexities associated with evaluating the reliability of pseudo-labels in a regression context. This paper introduces SimRegMatch, a novel semi-supervised regression (SSR) framework devised to overcome this specific challenge, by combining an uncertainty-based filtering mechanism with a similarity-based pseudo-label calibration approach. The former component is tasked with discerning which unlabeled examples possess pseudo-labels of sufficient reliability, achieved through the estimation of uncertainty levels. The latter component then refines these pseudo-labels by propagating information from labeled to unlabeled examples, thereby enhancing the overall quality of the pseudo-labels. The efficacy of SimRegMatch was rigorously tested through experiments conducted on the publicly available AgeDB dataset, which is centered around age prediction, as well as on a practical regression problem focused on the detection of interior noise levels in automobiles using accelerometer data. When benchmarked against current state-of-the-art methods in semi-supervised regression, SimRegMatch exhibited notable improvements in regression performance. Additionally, a series of ablation studies were carried out to dissect and understand the specific elements of the framework that were instrumental in achieving these performance enhancements. SimRegMatch addresses a pivotal issue in semi-supervised regression – the assessment of regression pseudo-label reliability – and substantially elevates model performance. By combining the strengths of uncertainty estimation and pseudo-label calibration, SimRegMatch emerges as a robust and versatile framework with significant potential for broad applicability in various SSR scenarios. A PyTorch implementation is publicly available at https://github.com/YongwonJo/SimRegMatch.