Scientific Method and Experimental Design
- 1. Scientific Method Hypothesis Controlled Experiment and Variable Independent and Dependent Variable Sample Size and Validity Scientific Method and Experimental Design
- 2. Steps of the Scientific Method Make observations. Ask a question. Form a hypothesis. Test the hypothesis. Analyze the results. Draw conclusions. Communicate the results.
- 3. Hypothesis An explanation of a natural event or observation that can be tested by additional observations or experimentation
- 4. Example of Hypothesis Observation: The population of tiger salamanders declined 65% between 1984 and 1988 Hypothesis: Acids that were formed in the upper atmosphere by pollutants were falling onto mountains in the winter snows
- 5. Controlled Experiment and Variable Tests one variable at a time (experimental variable) Controlled experiments include 2 groups: Experimental Group Exposed to experimental variable Control Group Not exposed to experimental variable
- 6. Independent and Dependent Variables Independent variable : The factor that is deliberately manipulated in an experiment (also called experimental variable) Dependent variable : The variable that is changed or determined by manipulation of the independent variable. It is what is measure in the experiment
- 7. Sample Size Sample Size (N) The number of subjects involved in experimentation Increasing N Decreases impact of chance events and error Increase reliability of results
- 8. Validity The extent to which experimental results can be generalized to other settings or situations To increase validity, increase N