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IEc develops statistical sampling plans for a wide variety of applications, including general population surveys, surveys targeting specialized groups, auditing applications, and program evaluations.

Sampling plans are customized for every situation, taking into account the characteristics of the population to be studied, cost factors, and client needs. Our experience covers a range of sampling approaches, including:

  • Simple random sampling;
  • Systematic sampling;
  • Stratified sampling;
  • Multi-stage sampling;
  • Cluster sampling; and
  • Probability-proportional-to-size sampling.
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UPPER COLUMBIA RIVER VISITOR SURVEY
IEc developed the statistical sampling plan for a 12-month, on-site survey of visitors to the Upper Columbia River in northeastern Washington to provide information to support a U.S. Environmental Protection Agency (EPA) human health risk assessment. The sampling plan for the survey involved a stratified, multi-stage cluster sample of visitors to ensure that survey respondents were well-distributed temporally and geographically while allowing for appropriate statistical inference.