Experimental Design


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Experimental Design

  1. 1. Experimental Design
  2. 2. What Makes a Good Experiment? There are several components of good experimental design.  Problem Statement  Hypothesis  Experiment  Data Collection  Conclusion
  3. 3. Example Experiment The experiment we will be looking at today is called “Drink, Drive, and Die”.  It was a science fair project by a student at Ashdown Junior High School in Ashdown, Arkansas.
  4. 4. Problem Statement The problem statement is the question that is being answered by the experiment.  In “Drink, Drive, and Die”, the problem statement is “Will drinking a small amount of alcohol decrease your reaction time and impair your ability to drive?”
  5. 5. Hypothesis A hypothesis is an educated guess.  Ex: “I believe, it will take at least one 12 oz beer, to affect your reaction time and impair your ability to drive.”  His hypothesis is an “educated guess” because of the research he had done on amounts of alcohol.
  6. 6. Experiment After you form your hypothesis, you test it. You must plan your experiment first. You need to decide on the number of replications, the control, and the variable.
  7. 7. Replication Replication is the repeating the experiment to check for consistency and accuracy.  If possible, you should always repeat your experiment at least once to be sure the results are consistent and accurate.
  8. 8. Sample Size Sample size is the number of repetitions you do.  Usually the bigger the sample size, the more accurate your experiment is.  Ex: If you wanted to find the mean (or average) height of your classmates and you measured the three shortest people, you would not get a very accurate result. If you measured all of your classmates, from the shortest to the tallest, your result would be more accurate.
  9. 9. Control Your control in your experiment is anything you use to provide a basis for comparing results or checking their accuracy; stays the same.  Ex: In “Drink, Drive, and Die”, the control was the “normal” reaction time. He compared the other reaction times to this control.
  10. 10. Variables A variable is a measurable aspect of an experiment that has different values under different conditions.  In “Drink, Drive, and Die”, the variables were the different amounts of beer.
  11. 11. Data Collection In order to collect good data, you must be a good observer. You need to pay attention to the things surrounding your experiment. After you collect your data, you must display it.  Ex: In “Drink, Drive, and Die”, he displayed his data in a line graph.
  12. 12. Conclusion In order to form your conclusion, you must analyze your data. This means to look at it carefully and decide whether or not your data supports your hypothesis.  Ex: In “Drink, Drive, and Die”, his hypothesis was supported by his data.