Beyond One-Size-Fits-All: A Differential Sensitivity Framework for Machine Learning–Based Detection of Anomalous Survey Responses

Anomalous survey responses, including random, careless, extreme, acquiescent, straightline, and alternating responding, threaten the validity of survey-based research. Machine learning (ML) algorithms offer flexible, model-agnostic alternatives to traditional detection methods, yet their relative effectiveness across anomaly types remains poorly understood. This study evaluated 11 unsupervised anomaly detection algorithms spanning four paradigms (distance-based, density-based, reconstruction-based, and tree/boundary-based) against six simulated anomaly types embedded in a realistic survey dataset ( N = 3,000). Results revealed pronounced differential sensitivity: globally deviant patterns (random, extreme, alternating) were universally detectable, whereas careless and acquiescent responding required reconstruction- or boundary-based methods, and straightline responding resisted detection by all algorithms (maximum area under the receiver operating characteristic curve AUC-ROC < .70). No single algorithm dominated across all types. These findings argue for multimethod approaches combining ML algorithms with traditional response quality indicators, and provide a framework for selecting detection methods based on anticipated anomaly types.