About Outlier Data
Audit Measures
For full details of the NPDA audit measures please visit www.rcpch.ac.uk/NPDA
Funnel Plots
Funnel plots can be generated for the key performance measures below, which show the variation in the achievement of all PDUs in England and Wales. The horizontal line within each funnel plot shows the national mean, the inside dotted lines indicate units whose results are within two standard deviations of this, and the outside line shows which units are three standard deviations outside. Depending on the measure, units above or below the dotted lines performed significantly better or worse than others. A result more than 2 standard deviations from the mean is deemed an ‘alert’; more than 3 standard deviations is deemed an ‘alarm’. The NPDA uses the adjusted mean HbA1c and the overall health check completion rate metrics as part of its formal outlier management process. From 2022/23, the health check completion rate metric has been updated to include children and young people with Type 1 diabetes of all ages, with outliers defined by percentage cutoffs rather than funnel boundaries. Details of performance on this metric are available here. Outlier data is not presented for 2020/21 as services were severely disrupted by pandemic-related restrictions.