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Experimental design verision 3
 

Experimental design verision 3

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In depth overview of scientific method and experimental design. Begins with big picture, then breaks down process with examples. In addition, discusses types of error, reliability and validity. ...

In depth overview of scientific method and experimental design. Begins with big picture, then breaks down process with examples. In addition, discusses types of error, reliability and validity. Designed for review for all students.

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    Experimental design verision 3 Experimental design verision 3 Presentation Transcript

    • 1. What is the experimental process? (Inquiry or Scientific method) 2. What are the key items to consider when designing an experiment? Goal: to answer these questions: schmied©2013
    • 1. What is the experimental process? Identify a Problem schmied©2013
    • Identify a Problem Make Observations Make Observations The basic steps Create a Testable question schmied©2013
    • 1. Identify a Problem c. Create a scientific Question a. Decide what to study b. Identify key elements (SS, MV, RV) schmied©2013 Ex: Will tulips grow faster with fertilizer?
    • Study Subject = Manipulated Variable = Responding Variable = How will adding fertilizer to tulips affect the tulip’s height? How will MV SS RV How will… MV and SS… affect…. the RV? Tulips Fertilizer Height Question Format: Writing Questions schmied©2013
    • 2. Form the Hypothesis Hypothesis = Prediction with a reason If, Then – compared to, Because format schmied©2013
    • If fertilizer is applied to tulips, Then the tulips with fertilizer will grow taller If, Then - compared to Prediction format compared to tulips without fertilizer MV SS Exp trial Definite prediction about RV Compare to Control Writing the Prediction 2. Form a Hypothesis schmied©2013
    • Because fertilizer has nutrients that increases tulip growth. Therefore tulips with fertilizer will grow taller. Hypothesis = Prediction with a reason If, Then – compared to, Because format Because includes SS, MV, RV & specific reasons why. Prediction: If fertilizer is applied to tulips, Then the tulips with fertilizer will increase in height compared to tulips without fertilizer…. Adding a reason MV Specific reasoning SS RV 2. Form a Hypothesis
    • 3. Perform an Experiment a. Materials d. Procedure b. Trials c. Variables schmied©2013
    • 3. Perform an Experiment a. Identify Materials schmied©2013
    • Question 1: What are the two types, or groups, of Trials in an Experiment ? Control and Experimental Trial! Question 2: What are the key differences between these trials? The Experimental Trial contains the Manipulated Variable & tests the Hypothesis. The Control trial results are compared to the Experimental Trial results 3. Perform an Experiment -> b. Trials schmied©2013
    • Example 3. Perform an Experiment schmied©2013
    • c. The World of Variables 3. Perform an Experiment schmied©2013
    • 3. Perform an Experiment schmied©2013 There’s only one MV in an experiment! There can be more than one RV in an experiment
    • What are two ways to control Variables? c. Controlling Variables 3. Perform an experiment schmied©2013
    • Create a Controlled Environment 3. Perform an Experiment One way is to: schmied©2013
    • Expose all trials to the same changing conditions. 3. Perform an Experiment Another way to control variables is to: schmied©2013
    • Identify ….. A Controlled variable? The Manipulated variable? The Responding Variable? An Uncontrolled Variable? 3. Perform an Experiment Tulip Height schmied©2013
    • d. Develop a Procedure a. Create list of Materials b. List procedural steps in order Identify trials Account for variables (only one MV!) Includes: i. Jobs ii. Safety Equipment (PPE) & hazards iii. Clean Up 3. Perform an Experiment schmied©2013
    • 3. Perform an Experiment – Its only as good as the data gathered. Week 1 schmied©2013
    • 3. Perform an Experiment Be consistent throughout the experiment. Week Three schmied©2013
    • 3. Perform an Experiment Ensure Reliability Repeat the experiment 3x schmied©2013
    • 8. Analyze the Data • Calculate Highs, Lows, Averages • Compare Experimental data to Control data • Look for Key Differences • Identify and Interpret patterns & variations • Make inferences from the data gathered • Identify sources of error schmied©2013
    • Error: What is error? An error is a mistake in perception, measurement or process. The types of error are: a. Experimental Design error: b. Operator Error. c. Observation Error: d. Recording Error: e. Calculation Error: f. Measuring tool limitation.
    • a. State the question b. Restate the Hypothesis c. Tell if Hypothesis is Accepted or Rejected i. Explain why using DATA (Hi, Low, Avg etc) 9. Develop a Conclusion: ii. Tell what you conclude from the data iii. Make inferences from the findings Clearly distinguish between the evidence and your explanations. iv. Evaluate the Reliability of the data v. Tell sources of error & effect on results vi. Describe how to increase the Validity. schmied©2013
    • schmied©2013 Elements of an experiment
    • To improve validity researchers do other trials to show that a change in the MV actually caused the change in the RV observed in their experiments. Improving Validity Let’s explore a couple ways that might improve the validity of the results from the Tulip experiment. Assume that the original class results show the tulips with fertilizer added actually grew taller. schmied©2013
    • A. Do more trials, each with different amount of fertilizer. Goal: See if a difference in tulip height can be linked to the amount of fertilizer given. Validity Example 1 schmied©2013
    • Daffodil Trials Week 8 b. Do more trials with another plant, like daffodils. See if adding fertilizer increases daffodil height. Validity Example 2 schmied©2013
    • c. Do Tulip trials with varying concentrations of fertilizer, but add Daffodil trials too. Validity Example 3 schmied©2013
    • 7. Communicate results to peers & defend. Information becomes part of the world of science. 1. State the Problem Take data Make Inferences from data about a problem. 1b. Create Question Develop question into potential experiment. Identify SS, MV & RV 2a Create Prediction Finalize details of Experiment….. Control & Exp Trials 2b. Form the Hypothesis 3. Do the experiment Gather data 4. Record & Analyze the data 6. Hypothesis accepted repeat 3x 5. Draw Conclusions Tell if Hypothesis was accepted or rejected discuss data and methods Hypothesis Rejected? start over Scientific Method schmied©2013