Staff cost per WAU: trust level and individual clinical service lines

Slightly different methodologies are used to calculate all staff cost per WAU (weighted activity unit) metrics at trust level and for individual clinical service lines. Find out more about the WAU and the basic cost per WAU calculation.

What are the differences and why

We use a simple calculation for staff cost per WAU metrics at clinical service line level, using data from ESR (the Electronic Staff Record) for costs:

Clinical service line pay cost per WAU = pay cost from ESR divided by number of WAUs for clinical service line></span> </p>

<p>Each metric has a page with the methodology, where you can see the exact codes we’ve used to extract the data from ESR and Reference Costs.</p>

<p>At trust level we use a combination of annual accounts and ESR data as the numerator in the calculation, depending on the type of staff cost metric we are calculating. 
This is because at trust level we need to take into account all staff costs including capitalised staff costs (such as those working on projects), and the differences between what’s reported in annual accounts, ESR and Reference Costs. For more information on the differences in reporting, see the <a title=

Where to find trust-level staff cost per WAU metrics

The more complex calculations, which use a combination of annual accounts and ESR data, are used for all staff cost metrics in the Pay section of Operational Productivity.

They also appear in:

  • Finance and Use of Resources (Use of Resources)
  • Workforce Analysis (Overview)
  • Nursing & Midwifery (Trust-level)
  • Allied Health Professionals (Money & resources)
  • Doctors (Overview)

Check the metric page to see exactly how it’s been calculated.

How we calculate trust-level staff cost per WAU metrics

For all these metrics we factor in Reference Costs as a percentage of operating expenditure (from annual accounts). This is abbreviated to OAF (operating expenditure adjustment factor) in the equations below.

We also apply a Market Forces Factor adjustment throughout.


Deriving costs for each group of substantive staff

We filter the data by ESR occupation code in order to calculate the cost per WAU for different staff groups such as medical, nursing or allied health professionals. We then use the same methodology as for the total substantive staff (above). See the methodology on individual metric pages for the ESR codes used, and get additional information from the NHS occupation code manual.

For staff cost per WAU metrics for individual clinical service lines, we also select the areas of work in ESR.

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