Netherlands National Drug Monitor - Research and Documentation ...

2009 Annual Report
This is the tenth Annual Report of the NMD. As in previous years, chapters two through
eight deal with developments per substance or classes of substances: cannabis, cocaine,
opiates, ecstasy and amphetamines, alcohol and tobacco. Because there are signs of
increasing popularity of GHB, a chapter of this substance has been added. In each
chapter we present a concise report on the most recent data about usage, problem use,
treatment demand, illness and deaths, as well as supply and market. The position of
the Netherlands is placed in an international perspective, but owing to methodological
differences, comparisons between countries should, however, be made with caution.
Chapter nine contains data on registered drug-related crime. Central to this is crime as
defined by the Opium Act and the criminal behaviour of drug users in various stages of
the law enforcement chain (police, Public Prosecutor, judiciary, custody). This chapter also
contains an up-to-date overview of the possibilities available to law enforcement agencies
for the compulsory and quasi-compulsory treatment of drug-addicted criminals.
Data on substance abuse and drug-related crime can be collected and represented in
different ways. Appendix A contains information on the terminology used. Appendix
B contains a concise overview of the most important sources of information for this
Report.
Statistical significance
This Annual Report describes trends in substance use and differences between groups
of users. In the case of data derived from a random population sample, we refer to
an ‘increase’ or ‘decrease’ only when statistically significant. This means that any such
change is unlikely to be by chance. At the same time, statistical significance is not entirely
straightforward. In very large samples, tiny differences can be significant, but may have
no practical meaning. Significance therefore does not always equate with relevance.
Conversely, there may be clear differences in user percentages that are not relevant
according to statistical analysis. This may be the case where samples are relatively small,
with considerable variation within groups. In such cases it could be that a larger sample
(for example more respondents) would yield a result that was significant.
In this Annual Report we regard statistical significance as guiding principle, but the size
of the differences is also important.
The NDM Annual Report may also be accessed as a pdf document on the following
websites: www.trimbos.nl. or www.wodc.nl.
32 Netherlands National Drug Monitor - NDM Annual Report 2009