Safer Surgery part 23. There have been few research investigations into how highly trained doctors and nurses work together to achieve safe and efficient anaesthesia and surgery. While there have been major advances in surgical and anaesthetic procedures, there are still significant risks for patients during operations and adverse events are not unknown. Due to rising concern about patient safety, surgeons and anaesthetists have looked for ways of minimising adverse events. | 194 Safer Surgery Performance Dimension Training PDT Increase rating accuracy by facilitating dimension-relevant evaluations. Behavioural Observation Training BOT Increase rating accuracy by focusing on the observation of behaviour. Frame of Reference training FOR Increase rating accuracy by focusing on the different levels of performance Salas et al. 2001 . Reportedly it is seemingly straightforward to train a single group of raters and achieve a relatively high level of inter-rater agreement and accuracy when compared to a standard set rated by an expert Salas et al. 2001 . The potential sources of error means that it is not as easy to translate this to many groups who are trained in separate centres or by different trainers. The rate of between-group rater agreement and accuracy is known to drop significantly without addressing such errors. Salas et al. 2001 outlined guidelines for training raters in the use of behavioural markers. These guidelines have been developed to try and minimize the sources of error described above. There is limited recent evidence on effective rater training in the medical domain and so these guidelines were followed to develop our rater training for ANTS. These guidelines were previously followed by Flin and Glavin s research group Fletcher et al. 2003 to evaluate inter-rater agreement for ANTS. Baker et al 2001 employed an eight-hour rater training programme for a behavioural marker system. They achieved an adequate level ofinter-rater agreement and accuracy in this time frame. Workpackage Report 7 from the University of Aberdeen investigating ANTS reports a four-hour training programme Fletcher et al. 2002 . With this minimal amount of training inter-rater agreement of rwg was achieved at an elemental level and for a categorical level. This was also without feedback and calibration. During the initial evaluation of ANTS by the Scottish team feedback from experts and calibration were deliberately excluded from .
