Figure 1.

The Structure of PREPs Awareness Questions. This figure shows that the initial distinction between question types is that they ask about PREPs in the abstract or they ask about specific PREPs brands. Within each of those groups, there are further divisions, as shown in the figure.

Bogen et al. Harm Reduction Journal 2009 6:27   doi:10.1186/1477-7517-6-27
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