Notes: Finished admission episodes: A finished admission episode is the first period of inpatient care under one consultant within one health care provider. Finished admission episodes are counted against the year in which the admission episode finishes. Please note that admissions do not represent the number of inpatients, as a person may have more than one admission within the year. Data quality: HES are compiled from data sent by more than 300 NHS trusts and primary care trusts in England. Data is also received from a number of independent sector organisations for activity commissioned by the NHS in England. The NHS Information Centre for health and social care liaises closely with these organisations to encourage submission of complete and valid data and seeks to minimise inaccuracies and the effect of missing and invalid data via HES processes. While this brings about improvement over time, some shortcomings remain. Assessing growth through time: HES figures are available from 1989-90 onwards. During the years that these records have been collected by the NHS there have been on-going improvements in quality and coverage. These improvements in information submitted by the NHS have been particularly marked in the earlier years and need to be borne in mind when analysing time series. Some of the increase in figures for later years (particularly 2006-07 onwards) may be due to the improvement in the coverage of independent sector activity. Changes in NHS practice also need to be borne in mind when analysing time series. For example, a number of procedures may now be undertaken in outpatient settings and may no longer be accounted for in the HES data. This may account for any reductions in activity over time. Source: Hospital Episode Statistics (HES), The Information Centre for health and social care: NHS Hospitals England and activity performed in the Independent Sector in England commissioned by English NHS.