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Kinds of Sampling

Kathryn Orzech
  • Support Material Type:
    • Vocabulary Words

This lesson asks you to use two different kinds of sampling to observe an animal or animals of your choosing. Here are the quick definitions of these kinds of sampling, plus one more you might want to use if you are observing a larger group of animals.

Ad libitum (Ad lib) sampling: Observer writes down anything that seems interesting. A good way to decide what behaviors are important for the animal you are studying.

Some Ad lib data from someone watching a group of monkeys might look like this:

  • 10:30 Adult male grooms another adult male
  • 11:14 monkey eats caterpillar
  • 12:05 Juvenile scans sky for 30 seconds

Focal animal sampling: Observer watches one animal for a set length of time and writes down everything that animal does, with times noted.

Some focal animal data watching the same group of monkeys might look like this:

  • 10:30 Big Boy (BB=focal animal) grooms another adult male
  • 10:33 BB stops grooming other male, looks up at juvenile female
  • 10:34 BB walks toward juvenile female
  • 10:35 BB distracted by pile of dirt

Instantaneous Scan sampling: Observer checks to see what each animal in the group is doing every time a pre-determined interval passes (15 seconds, for example).

Instantaneous scan sampling of the same group of monkeys might look like this:

  • 10:30:00 Male 1 grooming (G), Male 2 being groomed (BG), Female 1 digging in dirt, Female 2 nusing infant (N)
  • 10:30:15 Male 1 G, Male 2 BG, Female 1 looking at sky, Female 2 N
  • 10:30:30 Male 1 G, Male 2 BG, Female 1 looking at sky, Female 2 N
  • 10:30:45 Male 1 G, Male 2 BG, Female 1 looking at infant, Female 2 N 


Information on the Internet


Morbeck, Mary Ellen, Alison Galloway and Adrienne L. Zihlman, Eds. 1997. The Evolving Female: A Life History Perspective. Princeton University Press. Princeton, NJ.

Patterson, J.D. 2001. Primate Behavior: An Exercise Workbook, 2nd Edition. Waveland Press. Prospect Heights, Illinois.

About This Page

University of Arizona

Correspondence regarding this page should be directed to Kathryn Orzech at

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