Modified Target Diagram to check compliance of low-cost sensors with the Data Quality Objectives of the European air quality directive

The modified Target Diagram (MTD) was developed to evaluate the performance of low-cost sensors (LCS) for air quality monitoring in comparison with reference methods by reporting relative expanded uncertainty and its contributors. An MTD provides several pieces information, including compliance regulation, sources error how diminish them, completeness validity LCS calibration etc. It allows user examine effect selecting different regression types residual fitting on measurement uncertainty. ordinary least squared fitted residuals dynamic between analyser rather than constant ones yielded more realistic compared other options. is a fast visual tool extract information evaluation any candidate method against method.