Scattergraph Principles and Practice: Peeling the Onion — Evaluating the Accuracy of Flow Monitor Data

The scattergraph is a graphical tool that provides insight into sewer performance through a simple and intuitive display of flow monitor data. This tool can also be used to determine if the data provided are valid and suitable for further use. Precision and bias are the principle indicators of data quality and together provide a measure of accuracy. These indicators can be evaluated on a scattergraph at human viewing speed by comparing flow monitor data with manual confirmations and a pipe curve based on the Manning Equation. Practical examples from flow monitor locations throughout the United States are provided, demonstrating the scattergraph signatures of both valid and invalid flow monitor data.