Dennis R Helsel

Summary

Affiliation: U.S. Geological Survey
Country: USA

Publications

  1. ncbi request reprint Fabricating data: how substituting values for nondetects can ruin results, and what can be done about it
    Dennis R Helsel
    U S Geological Survey, P O Box 25046, MS 964, Lakewood, CO 80225, USA
    Chemosphere 65:2434-9. 2006
  2. ncbi request reprint Regional Kendall test for trend
    Dennis R Helsel
    U S Geological Survey, P O Box 25046, MS 964, Lakewood, Colorado 80225, USA
    Environ Sci Technol 40:4066-73. 2006
  3. ncbi request reprint Complications with using ratios for environmental data: comparing enantiomeric ratios (ERs) and enantiomer fractions (EFs)
    Elin M Ulrich
    U S Geological Survey, National Water Quality Laboratory, Denver, CO 80225, USA
    Chemosphere 53:531-8. 2003
  4. ncbi request reprint More than obvious: better methods for interpreting nondetect data
    Dennis R Helsel
    U S Geological Survey, Lakewood, CO, USA
    Environ Sci Technol 39:419A-423A. 2005
  5. ncbi request reprint Methyl tert-butyl ether (MTBE) in public and private wells in New Hampshire: occurrence, factors, and possible implications
    Joseph D Ayotte
    U S Geological Survey, NH VT Water Science Center, 361 Commerce Way, Pembroke, New Hampshire 03275, USA
    Environ Sci Technol 42:677-84. 2008

Collaborators

Detail Information

Publications5

  1. ncbi request reprint Fabricating data: how substituting values for nondetects can ruin results, and what can be done about it
    Dennis R Helsel
    U S Geological Survey, P O Box 25046, MS 964, Lakewood, CO 80225, USA
    Chemosphere 65:2434-9. 2006
    ..Substituting values for nondetects should be used rarely, and should generally be considered unacceptable in scientific research. There are better ways...
  2. ncbi request reprint Regional Kendall test for trend
    Dennis R Helsel
    U S Geological Survey, P O Box 25046, MS 964, Lakewood, Colorado 80225, USA
    Environ Sci Technol 40:4066-73. 2006
    ..Yet often also of interest is whether a consistent trend is evident throughout the entire region. This paper adapts the Seasonal Kendall trend test to determine whether a consistent regional trend occurs in environmental variables...
  3. ncbi request reprint Complications with using ratios for environmental data: comparing enantiomeric ratios (ERs) and enantiomer fractions (EFs)
    Elin M Ulrich
    U S Geological Survey, National Water Quality Laboratory, Denver, CO 80225, USA
    Chemosphere 53:531-8. 2003
    ..The use of nonparametric statistical summaries, e.g., median and percentiles, provides a more robust indicator of the typical value and spread for both ER and EF data...
  4. ncbi request reprint More than obvious: better methods for interpreting nondetect data
    Dennis R Helsel
    U S Geological Survey, Lakewood, CO, USA
    Environ Sci Technol 39:419A-423A. 2005
  5. ncbi request reprint Methyl tert-butyl ether (MTBE) in public and private wells in New Hampshire: occurrence, factors, and possible implications
    Joseph D Ayotte
    U S Geological Survey, NH VT Water Science Center, 361 Commerce Way, Pembroke, New Hampshire 03275, USA
    Environ Sci Technol 42:677-84. 2008
    ..From 2003 to 2005, MTBE occurrence decreased in 63 public-supply wells and increased in 60 private-supply wells, but neither trend was statistically significant...