BIO 109 Home
Questions | Answers

1. A way of knowing about the natural world using a process designed to reduce the chance of being misled.

2. Process:

  • Observation
    • Go see your friend's fish pond to confirm the absence of fish
  • Question
    • Ask, "Why have my neighbor's fish died in the pond?"
  • Literature Review
    • Read the literature to find out the survival requirements for the fish that were in your neighbor's pond and to find out about past reasons fish have died in ponds.
  • Multiple Hypotheses
    • The fish died because the water was too cold.
    • The fish died because there was not enough oxygen.
    • Etc.
  • Deductions
    • If the fish died because the water was too cold, then the water temperature must be below 40 degrees to kill the fish.
  • Tests
    • Measure the temperature of the water.
  • Tentative Conclusions
    • The fish died because the water temperature was too cold (it was 30 degrees and the lethal lower limit is 40 degrees).
  • Peer Review
    • I would submit my report to a scientific journal.

3. Rules

  • Maximize Sample Size
    • Collect data from as large a sample as possible (for the quiz, use at least 1000).
      • Example: if you want to know the average height of PCC students, you should measure thousands of students.
  • Representative Sample
    • Choose the sample from the population you are interested in and choose the sample randomly or systematically to avoid bias.
      • Example: if you want to know the average height of PCC students, you can't just measure the height of all the basketball players. You should randomly choose 5000 students from a list of all students.
  • Controlled Studies
    • Always have two groups at least: a control group and an experimental group. Both groups should be treated exactly the same with only one variable different. Compare results between the two groups so you can be more sure that any effects seen in the experimental group that are not seen in the control group likely arose from the variable that differed between the two groups.

4. Definitions:

  • Hypothesis: a possible answer to the question.
  • Theory: conceptual framework that explains a variety of observations, is supported by experimental evidence, and is capable of predicting new phenomena = as sure as science ever gets.
  • Independent Variable: the potential cause of an effect.
  • Dependent Variable: the effect (is affected by the independent variable)
  • Controlled Variables: anything else, besides the independent variable, that could influence the dependent variable.
  • Experimental and Control Group: Both groups must be as exactly the same as possible with the exception that the experimental group differs in one aspect (the independent variable).

5. Research Question format: Is there a difference in [dependent variable] between [independent variable]? Don't forget the question mark.

6. The dependent variable is precipitation because it is affected by elevation. The independent variable is elevation because it affects precipitation. A controlled variable would have to be season, because season also affects precipitation. The research question would be: Is there a difference in precipitation between areas at different elevations?