The Scientific Method

1. The Scientific Method

2. What is Science? • “Science” derived from Latin ‘to know’ • Way of asking and answering questions about the world around us • Can only address questions that are testable • Scientific thinking reduces personal, emotional reactions

3. Scientific Design • Scientific method – common steps that scientists use to gather information and answer questions • There is no ONE scientific method. • This is just a general outline to follow.

5. Observing • An observation is made about the natural world. • Songbirds seems to be absent in the forests of Guam. • This observation was made around the same time that brown tree snakes were first spotted in Guam. • The scientist will then develop a general question that they are setting out to answer. • Example: Is there a relationship between the lack of songbirds in the forests in Guam and the introduction of the brown tree snake?

6. Hypothesis • Hypothesis – a possible explanation for a question or problem that is testable and based on previous knowledge • It is NOT an “educated guess” • Example: The brown tree snake is eating the song birds.

7. Controlled Experimentation • Controlled experiment – an investigation that tests a hypothesis by the process of collecting information under controlled conditions • Made up of: • Independent variable • Dependent variable • Control group • Experimental group • Controls

8. Experimental Design Independent (manipulated) variable: condition or event under study Dependent (responding) variable: condition that could change under the influence of the independent variable (measure this) Controls (controlled variables): conditions which could effect the outcome of the experiment so they must be held constant between groups

9. Experimental Design Experimental group: group(s) subjected to the independent variable Control group: group kept “normal”, used as measuring stick

10. Data Analysis and Conclusions • Data – information obtained from investigations • Qualitative data: observational data • Example: color changes, descriptions • Quantitative data: numerical data • Example: time, quantities, measurements • Examine the data for patterns and trends and make conclusions from the data that you collected.

11. Publishing Results • Scientists then publish and share their data through scientific journals so that other scientists can review and use this information. • Science is collaborative and results must be reproduced and verified in order to be commonly accepted.

12. Theories and Natural Laws • Theory: a description of the world that covers a relatively large number of phenomena and has met many observational and experimental tests • Law of Nature: theory (or group of theories) that has been tested extensively and seems to apply everywhere in the universe

13. Example • Observation: Dogs that wear the red collar seem to have less fleas. • Hypothesis: The red collar keeps fleas from the dog.

14. Experimental Design • Obtain 500 dogs of various breeds from local shelters. • Randomly assign individuals to 2 groups. • What would you do to the experimental group? • What would you do to the control group? • Board the dogs in identical environments and treat them the same except for the independent variable. • What is the independent variable? • After 2 weeks the dogs are examined. • What is the dependent variable? What are we measuring?

15. Results: The dogs wearing the red collars were virtually free of fleas after the 2 week period. The dogs without the collars had about the same number of fleas as when the experiment began. What can we conclude??