text: The DIP cohort has a far older age profile even than the 2014 cohort of treatment initiates, who 
  themselves have a far older age-of-initiation profile than previous treatment cohorts. As such, it 
  seems highly unlikely that all, or even most, of the 4,281 positive testers in 2013 are new 
  initiates. 
  
  Of course, even if just the small number of DIP testers (78716) who were aged under 25 in 2013 
  were considered to be new initiates, this would still need to be multiplied up by three factors to 
  provide an estimate for total new initiates: i) the non-arrest rate (to account for the fact that only 
  a proportion of crime-involved initiates will get arrested in a given year); ii) the fact that DIP’s 
  coverage (in terms of age, geography and PNC-referenced individuals) is not 100 per cent; iii) 
  the likelihood that up to half of all new initiates will not be involved with crime at all. As an 
  illustration, multiplying up 787 by these factors produces a figure close to 10,000.17 
  
  These calculations are speculative and based on a number of assumptions. They are intended 
  as a sense-check on the results for the next section. The fragility of the modelling should not 
  detract from the simple fact that the absolute number of new positive testers in 2013 is low 
  relative to the estimated size of the total population. This alone suggests that numbers of new 
  users in 2013 is markedly lower than in previous years. 