Leveraging Approximate Constraints for Localized Data Error Detection

Error detection is key for data quality management. AI techniques can leverage user domain knowledge to identifying sets of erroneous records that conflict with domain knowledge. To represent a wide range of user domain knowledge, several recent papers have developed and utilized soft approximate constraints (ACs) that a data relation is expected to satisfy only to a certain degree, rather than completely. We introduce error localization, a new AI-based technique for enhancing error detection with ACs. Our starting observation is that approximate constraints are context-sensitive: the degree to which they are satisfied depends on the sub-population being considered. An error region is a subset of the data that violates an AC to a higher degree than the data as a whole, and is therefore more likely to contain erroneous records. For example, an error region may contain the set of records from before a certain year, or from a certain location. We describe an efficient optimization algorithm for error localization: identifying distinct error regions that violate a given AC the most, based on a recursive tree partitioning scheme. The tree representation describes different error regions in terms of data attributes that are easily interpreted by users (e.g., all records before 2003). This helps to explain to the user why some records were identified as likely errors. After identifying error regions, we apply error detection methods to each error region separately, rather than to the dataset as a whole. Our empirical evaluation, based on four datasets containing both real world and synthetic errors, shows that error localization increases both accuracy and speed of error detection based on ACs.