Tutorial on risk adjusted X-bar charts: applications to measurement of diabetes control

Two data elements are needed for constructing a risk-adjusted X-bar chart. They are a continuous observed outcome collected over time across a sample of patients, and an expected outcome for each patient. The authors selected blood glucose levels to reflect diabetes control. They then reviewed data showing blood glucose levels of 60 Type 2 diabetes patients in a family practice clinic of five providers. The data covered a period of 21 consecutive months. They present the data relating to two of the providers using this set of data to demonstrate how to create a risk-adjusted X-bar control chart.