Slide 1The Scientific MethodThe Scientific Method: The HypothesisThe Scientific Method: Experimental DesignSlide 5Scientific PapersSlide 7Slide 8Slide 9Slide 10Chapter 1The Scientific Method•Steps to the scientific method are:1. Observation/ Question2. Hypothesis a. Null hypothesis (H0)b. Alternate hypotheses (Hn)3. Experimental Design4. Data Collection/ Analysis5. ConclusionsThe Scientific Method: The Hypothesis•After making observations, scientists formulate a hypothesis (plural: hypotheses).•A hypothesis is an educated guess about the answer to a question raised during observation.•Scientists formulate a null hypothesis and alternative hypotheses.The Scientific Method: Experimental Design•What will you measure? How?•What will your sample size be? How will you ensure that your sample reflects the entire population? •How will you keep variables that are not being measured controlled between the groups? Controls (Negative and Positive controls)•How will you analyze your data?Statistical Analysis of Data Descriptive analysis - used to show patterns in data•Mean•Median•Standard deviation•Standard error•Confidence intervalComparative - used to compare means of groups of data•Paired t-test•ANOVAFrequency - used to compare experimental results with expected results.•Chi squared testScientific Papers•Scientists communicate their findings and conclusions in scientific papers. Scientific papers are of two types:1. Review articles: Review articles generally do not present new data; they analyze data and conclusions taken from other papers. 2. Primary journal articles: Primary articles are written by the person(s) who actually performed the experiments, and collected the data from those experiments.Reading a Scientific PaperDiscussion of Xie et. al. (1998) JBC 273(19):11576-82.1) Title2) Abstract- Summary3) Introduction- Background information needed to understand experiments performed and why.4) Materials and Methods- How to reproduce same results5) Results- What scientists found and only what was found, no interpretations of results here.6) Discussion- How the results reflect on hypothesis, conclusions made from results.7) ReferencesBiology 302 Lab Report Rubric (Point value in parentheses)1. INTRODUCTION (10)Context (4)Accuracy and relevance (3) Hypothesis (3)2. MATERIALS & METHODS (5) Procedure, Controls & Replication 3. RESULTS (10)Data Selection (4)Data Presentation (6) 4. DISCUSSION (20)Conclusions based on the data selected (10)Alternative explanations / Limitations of data (5)Significance of research (5)5. WRITING QUALITY (5)Today’s ExerciseCommon search engine - PubMed at: http://www.ncbi.nlm.nih.gov/entrez/query.fcgiRecognize the difference between primary journal articles and review articlesExercise 1.1: Review articles and primary articles 1. Find review article:“The HL-60 promyelocytic leukemia cell line: proliferation, differentiation, and cellular oncogene expression” by S. J. Collins (1987) Blood 70, 1233-1244. 2. Find primary article:“Fibronectin-mediated Cell Adhesion Is Required for Induction of 92-kDa Type IV Collagenase/Gelatinase (MMP-9) Gene Expression during Macrophage Differentiation” by Bei Xie et al. (1998) J. Biol. Chem. 273 (19), 11576-11582.3. Save a copy of the files and send them to your email.4. Read through the review article (Collins, 1087) before next class for discussion.If its not in the lab manual, its on Blackboard or the
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