• Numerator: Number of physicians, nurses and midwives (depending on the original data source, this may include personnel who are active only, or all personnel registered in the relevant health occupations), defined in headcounts, multiplied by 10,000
• Denominator: Total estimated population size

Step 1) Extract the density (per 10,000 population) of medical doctors, nursing personnel, and midwifery personnel from the WHO National Health Workforce Accounts (NHWA) data portal.

Step 2) Sum the total number of medical doctors, nursing personnel, and midwifery personnel for each WHO Member State.

Step 3) Extract the latest national populations estimates from the most recent revision of the UN Population Division’s World Population Prospects (UNPD WPP) database.

Step 4) Calculate a population-weighted average of density for each Member State by multiplying the density (per 10,000 population) of specified health personnel by the latest UNPD WPP estimate of national population size.

Step 5) To calculate global and regional aggregate densities, divide the sum of UNPD WPP population estimates for all Member States in a particular area (global or regional) by the sum of population-weighted densities (density per 10,000 population multiplied by estimated population size) of all Member States in the same area.

Limitations on health workforce data:

• Data on health workers tend to be more complete for the public health sector and may underestimate the active workforce in the private, military, nongovernmental organization and faith-based health sectors. In many cases, information maintained at the national regulatory bodies and professional councils is not updated.
• As data is not always published annually for each country, the latest available data has been used. Due to the differences in data sources, considerable variability remains across countries in the coverage, periodicity, quality and completeness of the original data. Densities are calculated using national population estimates from the UN Population Division's World Population Prospects database and may vary from densities produced by the country.
• Continuous data quality improvement processes and country data updates may result in observed differences across versions of data published on the NHWA data portal.

• Variability in reliability and timeliness of demographic data (e.g., if a recent census is not available for a country, estimates are projected using historical data)