The Council for Medical Schemes (CMS) routinely collects summarised data from medical schemes through the mechanisms of Statutory Returns. The CMS collates this information and publishes the results in the form of an annual report. The collated industry data is relied upon heavily by industry stakeholders, regulators and market commentators. It is therefore critical that the data be reliable. When considering industry data such as that published by the CMS it is important to understand the limitations of the data.