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1.5 PDQ. 1.5 1. Scientific Process 5 Steps. Make observations Ask a question Form a hypothesis to answer the question Make a prediction based on a true hypothesis Design and conduct an experiment that uses quantifiable data to test your prediction. What happens after #5?.
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1.5 1. Scientific Process 5 Steps • Make observations • Ask a question • Form a hypothesis to answer the question • Make a prediction based on a true hypothesis • Design and conduct an experiment that uses quantifiable data to test your prediction What happens after #5?
1.5 2. Deductive Logic, Relationship between observation, hypothesis design, and prediction • Starts with a statement believed to be true and goes on to predict what facts would also have to be true to be compatible with that statement. • Hypothesis design is based on your observations and your prediction is based on a true hypothesis
1.5 3. What are the elements of a well designed, controlled experiment? List and define. • Independent variable – variable that is manipulated in an experiment • Dependent variable – variable that responds to the manipulative variable in the experiment • Constants – all other variables in an experiment which must stay the same * See syllabus packet
1.5 4. Explain difference between controlled experiment and comparative experiment Controlled Comparative Comparing groups or samples Do not control variables • 1 manipulative variable • All other variables are the same
1.5 5. Explain the value of a statistical test and the null hypothesis • Statistical tests calculate the probability that the differences observed between measurements could be due to random variation. • Null hypothesis tests that there is no effect. It is the premise that any observed differences are simply the result of random differences
1.5 6. Tyrone Hayes Case • Dependent variable – gonadal abnormalities % in male frogs. Independent variable – amount of atrazine (ppb) • Constants – tanks, same type of tadpoles, amount of tadpoles in each tank • Graph used – bar graph
6. continued…d. Environmental factors • Other toxins at the site – cannot control what was already present in the water • DNA – cannot control genes and their expression or mutations that may result • Any others? *Scientists could run other experiments to see if these variables alone are causing abnormalities.