The Risk Adjusted Mortality Index (RAMI) is calculated as the ratio of the actual number of deaths in a hospital, compared to the expected number of deaths.
The baseline is set at 100 - so anything above that means a higher than expected death rate, and anything below it means a lower than expected death rate.
Here are the figures for Wales' district general hospitals, for October 2011 to September 2012:
- University Hospital of Wales, Cardiff - 128
- Llandough, Penarth - 86
- Prince Charles, Merthyr Tydfil - 102
- Royal Glamorgan, Llantrisant - 119
- Royal Gwent, Newport - 117
- Nevil Hall, Abergavenny - 86
- Morriston, Swansea - 102
- Singleton, Swansea - 102
- Neath Port Talbot, Port Talbot - 102
- Princess of Wales, Bridgend - 102
- Bronglais, Aberystwyth - 95
- Glangwili, Carmarthen - 95
- Prince Philip, Llanelli - 89
- Withybush, Haverfordwest - 97
- Ysbyty Gwynedd, Bangor - 108
- Ysbyty Glan Clwyd, Bodelwyddan - 103
- Wrexham Maelor, Wrexham - 117
More top news
The Prince of Wales was treated to a piano performance at Buckingham Palace night by a nine-year-old girl from Llanharan.
A clear-up continues after the damage caused by Storm Imogen. Winds over 80mph battered the coast and thousands were left without power.
A three-year-study by the Office for National Statistics surveyed 300,000 people and reveals which of Wales' counties is 'happiest'.