Frequent Questions

Why would I want to perform double sampling?

When the retrospective power of a set of samples is below the required design objectives, double sampling can raise it. Insufficient retrospective power can occur for a number of reasons, most commonly because:

  • The spatial variability in residual radioactivity concentrations is larger than anticipated.
  • Samples were lost, did not pass analytical QA/QC, or were otherwise unavailable for inclusion in the analysis.

For more information on the MARSSIM process, visit MARSSIM on EPA.gov.

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