Why are there fluctuations?

Please exercise care when comparing HES figures for different years.

Fluctuations in the data can occur for a number of reasons, eg organisational changes, reviews of best practice within the medical community, the adoption of new coding schemes and data quality problems that are often year specific. These variations can lead to false assumptions about trends.

We advise users of time series data to carefully explore the relevant issues before drawing any conclusions about the reasons for year-on-year changes.