In order to analyze a sample, it must first be collected. While this may seem obvious, the importance of collecting a representative sample cannot be overstated. If the sample is not representative, the analysis is worse than useless; it could be misleading and result in changes in treatment that are unnecessary and potentially damaging to the treatment process.
The most important part of the analytical process is the collection of representative samples. Many lab errors are the result of improper sampling. The goal of sample collection is to collect a sample that is truly representative of the conditions that exist at the time of collection.