Effective Experimental Design for Ecology and Environmental Science

1
Effective Experimental Design for Ecology and
Environmental Science
2
Topics for Free Response QuestionFor Ch. 3 4
APES Test

• r-strategists for reproduction
• K-strategists for reproduction
• Graph interpretation
• Food web sketch
• Experimental design
• IPM Integrated pest management

3
Must haves

• Must have a hypothesis to address a question, a
  problem, a cause and effect
• Must have measurements and keep records of data
  (a count, a weight, a time, a percent, etc)
• Must be done over a reasonable amount of time
  (usually not a few days or months, often needs a
  year or more, one full cycle or stage of life is
  necessary)
• Must use a control group (one with the tested
  variable held constant, or one with the absence
  of the variable to be tested)

4
Hypothesis

• An actual prediction, educated guess, not just
  restating a question
• Must specify the direction and/or type of change,
  not just that a change will happen
• Could be the null hypothesis there is no
  relationship, no cause and effect, e.g. the
  number of tomato worms in a garden will have no
  impact on the number of tomatoes produced

5
Experimental Type

• Need at least two sites, one with tested variable
  (experimental site) and one without (control
  site)
• A variable is manipulated (either natural or in a
  lab) and consequences are observed

6
Observational Type

• Student is NOT manipulating a variable
• Student makes long term measurements and
  statistical analysis to determine IF there is any
  significant correlation between variables or
  poplulations
• Often an experimental site can be compared to a
  baseline site, but two sites are not needed