Among other measures of data quality, determining the reliability of conflicting values from different sources is especially challenging. Traditional data fusion approaches often infer correct values in simple cases, but struggle to handle variations in data granularity (such as differences in temporal, spatial, or categorical aggregations) and offer limited insight into the nature of disagreements. Thus, we propose a new source evaluation approach for numerical attributes that measures discordance (i.e., the extent to which sources differ from each other). Unlike existing methods that focus solely on point estimation, we allow both fine-grained and coarse-grained analysis, allowing more sophisticated data quality assessments. We employ a linear programming solver that transparently adapts to any data alignment expressed in a set of operators resembling relational algebra. Extensive experiments on real-world datasets demonstrate that our method generalizes existing truth discovery techniques measuring differences with Mean Absolute Error (MAE), Root Mean Square Error (RMSE), and can adapt to diverse and complex scenarios.