1.2 The Scientific Process PDF

Today we will answer: What is science? How does science work? What is a hypothesis? How is it different from a theory? What is a control? Why is it important? What are the differences between longitudinal cohort, case-control, and randomized trials? When might you use each? Figure 1.1...

Today we will answer: What is science? How does science work? What is a hypothesis? How is it different from a theory? What is a control? Why is it important? What are the differences between longitudinal cohort, case-control, and randomized trials? When might you use each? Figure 1.1 What can this Beach Mouse (Peromyscus Polionotus) Teach us about Biology? Not quite! Simplified View of Scientific Process Discussion Talk to your neighbor about the question: Is it safe to drink coffee during pregnancy? Each student should write their answer to: What is wrong with this question? Rephrase it so that it is an appropriate scientific question. Independent vs Dependent variables Independent variable: not changed by other variables Dep. Var. (“exposure”) Thing we are testing effect of We can change this or observe it Dependent variable: affected by change in independent variable (“result”) Thing we are measuring Indep. Var.  Independent vs Dependent variables Independent variable: not changed by other variables (“exposure”) Dep. Var. Thing we are testing effect of We can change this or observe it Dependent variable: affected Indep. Var. by change in independent variable (“result”) Thing we are measuring  Griffith’s Experiment (1928) Pneumonia is an infection of the lungs Caused (often) by the Dangerous strain has “capsule” – looks smooth (S strain) bacterium Streptococcus Less harmful strain looks rough (R strain) pneumoniae Griffith’s Experiment (1928) Frederick Griffith Griffith’s Experiment (1928) Frederick Griffith  Causation and Correlation Just because two things show up together doesn’t mean that one caused the other! Could be unrelated Could be caused by same thing “Confounding variables” Statistics needed to determine actual causative relationships! Causation and Correlation  Human Studies and Study Types Cross-sectional vs. Longitudinal  Studies and Study Types Prospective vs. Retrospective Prospective Exposure Result ? ? Retrospective Exposure Result ? ?  Cohort Studies Starts with exposure Nicotine, genes, diet, etc. Looks for correlation with disease Can be prospective or retrospective Best when prospective  Case-control studies Starts with disease Looks for correlation with exposure Retrospective  Clinical Studies Prospective Identify susceptible population Assign to different groups (usually randomly) Single-blind: study group does not know Expose groups which group they are in differently Double-blind: neither study group nor Determine outcome investigators know For Friday: Know the basic meaning of the following: Atom Ion Electron Element Proton Valence shell Molecule Neutron Ionic vs Covalent Bonds If you need a review, look on Canvas for review lectures