  In 2004, the UK Government's Department for Environment, Food and Rural
Affairs commissioned research with the aim of developing a scheme for assessing
the risks posed to species, habitats and ecosystems in the UK by non-native
organisms. The outcome was the UK Non-Native Organism Risk Assessment Scheme.
Unfortunately, the mathematical basis of the procedure for summarising risks
deployed in the Risk Assessment Scheme, as outlined in Baker et al. (2008) and
described in more detail in the Risk Assessment Scheme's User Manual, contains
several analytical errors. These errors are outlined in the notes that follow.
