Scientific Method Biology Image from:

What is Science? Science: – is guided by natural law – must explain what is observed with reference to natural laws e.g., biological, physical, chemical – is testable against the empirical world – has conclusions that are tentative pending additional information – is potentially falsifiable e.g., T-rex is a fierce predator

Ways of Knowing Experience Intuition Religion Science

The Scientific Way of Knowing The study of reality focusing on the material or natural aspect of the universe. How do we acquire knowledge? – Observation, empirical investigations, analysis, dedication and conclusion How do we validate? – Public, objective, consistent, observable, natural, predictable, testable, tentative

A Few Important Definitions Scientific Hypothesis: A testable statement about the natural world (that can be used to construct more complex inferences and explanations – theories) Example – Plants need water to grow.

Scientific Fact: An observation that has been repeatedly confirmed Example – distribution of fossils in strata tell us age of fossil Example – Humans have 46 chromosomes under normal conditions.

Scientific Law: A descriptive generalization about how some aspect of the natural world behaves under stated conditions Example – Newton’s Three Laws of Motion

Scientific Theory: A well-substantiated explanation of some aspect of the natural world (that can incorporate scientific facts, laws, inferences, and tested hypotheses) Example – cell theory, heliocentric theory, plate tectonic theory, gravitational theory, evolutionary theory, etc.

What are the Rules for Scientific Theories? A statement that attempts to describe and explain a natural phenomenon. Must be testable Must have predictive power Cannot appeal to supernatural agents Has been tested over and over and over again. Usually not refuted – Just make minor changes.

What is the Scientific Method? A structured way of investigating and evaluating theories. What are the steps? – Observation – Information – Hypothesis – Experiment – Results – Conclusion

Observation Experience a phenomenon that leads to a question

Information Gather background information to form an educated hypothesis

Hypothesis Putting your question into a testable format.

Experiment Design, setup and conduct a test to accept or reject the hypothesis

Results Collect and analyze the data (typically complete statistical analysis)

Conclusion Interpret data, summarize results, accept or reject hypothesis, and consider ideas for future research.

The Cycle Initial Observation Gather Informatio n Draw Conclusio n Perform Experimen t Gather Results Form Hypothesis

New Model of Investigation

Experimental Design Variables Controls T-Test Statistical Significance Validity