Upper Mississippi River Restoration Program Long Term Resource Monitoring

Estimating means and temporal trends using LTRM data: details with examples

Estimating population means

LTRM sampling sites are selected at random from strata. Hence, design factors are not considered when estimating an annual stratum mean from LTRM data. Such factors, however, do need to be considered when estimating a mean from more than one stratum, from a portion of a stratum or from multiple years. Approaches for addressing each of these scenarios are provided below.

• Estimating a stratum-specific mean for a single year
  
  
• Estimating a multi-stratum mean for a single year
  
  
• Estimating a mean from multiple years
  
  
• Estimating means from portions of one or more strata

Contact: Questions or comments may be directed to Brian Gray, LTRM statistician, Upper Midwest Environmental Sciences Center, La Crosse, Wisconsin, at brgray@usgs.gov.