Notes:
Data for Spain 1999; Age range 15-34.
Cannabis and other drug users are defined as having used the substance during the past year.
These examples and the following text are based on analysis of data in the general population survey databank carried out by Dr Harry Sumnall, Liverpool John Moores University, UK. Managed by Julian Vicente, EMCDDA.
Conditional prevalences of substance use across periods are calculated (i.e. the prevalence of use of drug B considering use of drug A has already occurred).
The calculation shows the association between prevalence of drug B in those individuals reporting use of drug A.
See also 'General notes for interpreting data' on the Explanatory notes and help page.
Sources:
Sumnall, Spain 1999.