text: This lends a certain degree of confidence to the findings and suggests that the variation in 
  geographical coverage from 2006 onwards will not bias the findings greatly. However, a few 
  caveats need to be mentioned. 
  
  i) The above percentages only excluded LAAs that did not record any cases for the entire 
  
  year. It is possible some LAAs only recorded cases for certain months within a 
  particular year. 
  
  ii) Many of the findings from the report exclude cases in which no Police National 
  Computer (PNC) number was recorded. Looking at the data it is clear that the 
  proportion of cases without a PNC number varies across areas. So this will introduce 
  some geographical bias. 
  
  iii) Using the published OCU figures by LAA to estimate DIP’s geographical coverage 
  
  involves the assumption that OCUs tend to get arrested in the same area in which they 
  live and receive treatment. 