Examining document model residuals to provide feedback during information retrieval evaluation

Evaluation of document models for text based Information retrieval is crucial for developing document models that are appropriate for specific domains. Unfortunately, current document model evaluation methods for text retrieval provide no feedback, except for an evaluation score. To improve a model, we must use trial and error. In this article, we examine how we can provide feedback in the document model evaluation process, by providing a method of computing relevance score residuals and document model residuals for a given document-query set. Document model residuals provide us with an indication of where the document model is accurate and where it is not. We derive a simple method of computing the document model residuals using ridge regression. We also provide an analysis of the residuals of two document models, and show how we can use the correlation of document statistics to the residuals to provide statistically significant improvements to the precision of the model.