Monterey Bay Aquarium Research Institute
Edward T. Peltzer
How it is done: Using MATLAB®

Model I and Model II Regressions

  • A basic introduction to Model I and Model II linear regressions:
    • what they are,
    • how they are different,
    • why they are different,
    • and when to use them.
  • A brief history of Model II regressions.
    • Who led the intellectual development of these regression techniques.
    • Plus, a list of their seminal papers.
  • An index of downloadable files for use with MATLAB®.
    • Model I regressions: normal (Y-on-X), reversed (X-on-Y) and weighted (wY-on-X).
    • Model II regressions: major axis, geometric mean and least-squares-cubic.
    • Summary of modifications made to these files.
  • Some rules of thumb to help decide which model regression to use:
    • When to use Model I vs Model II.
    • Within each type, which of the various models to use.
  • Testing Model I and Model II regressions:
    • Here's a way to test and compare your linear regression routine against mine.
      • Download the data file. ASCII text file format
      • Examine the results from the various regression models.
      • View graphs of the various regression models in gif or postscript format.
    • How to know which regression you are using.
  • For further reading regarding Model I and II regressions, see:
    • Ricker (1973). Linear regressions in Fishery Research. J. Fish. Res. Board Can. 30: 409-434.
    • Laws and Archie (1981). Appropriate use of regression analysis in marine biology. Marine Biology 65: 13-16.
    • Sokal and Rohlf (1995). Biometry, 3rd edition. W.H. Freeman and Company, San Francisco, CA.
    • Laws (1997). Mathematical Methods for Oceanographers. John Wiley and Sons, Inc., New York, NY.
Last updated: May 18, 2009
Questions? Comments? Please contact Edward Peltzer.