1. Assessing the context

Collecting, preserving, processing or analyzing a sample is expensive, and even more so if you try to reduce the cost too much. In fact, if one or other of these stages is neglected, it may look as if savings have been made, but in reality, the money spent will have been for nothing or next to nothing.

Whether or not to take a sample must therefore be examined, first and foremost, by asking the eternal questions: Why? Why? When? Who? For what purpose?