2.3 Foundational Concepts of Sampling
As previously mentioned, the fundamental purpose of sampling is to obtain data that will support decision making about an area or volume of material that is impractical or impossible to analyze in its entirety. For example, consider a volume of soil that has been defined as an exposure area for risk assessment, such as the top 2 inches in a residential yard. A decision is to be made about this volume of soil based on the mean contaminant concentration. The ideal way to estimate the mean concentration would be to collect and analyze the top 2 inches of soil from the entire yard. This method would provide an excellent estimate of the mean contaminant concentration in the yard but clearly this is impractical. Therefore, samples must be collected and conclusions drawn about the yard from the results of those samples.