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1 1 data

  1. 1. A Statistical Investigation <ul><li>State your claim </li></ul><ul><li>Collect your data </li></ul><ul><li>Calculate the appropriate values </li></ul><ul><li>Run the tests to see if we accept or reject the claim </li></ul>
  2. 2. A Statistical Investigation <ul><li>Starts with a claim </li></ul><ul><li>South students are smart!! </li></ul><ul><li>“ But all the kids have their own car!!” </li></ul><ul><li>Or a question </li></ul><ul><li>Are Japanese cars safer than European cars? </li></ul><ul><li>Is chocolate more popular that vanilla? </li></ul>
  3. 3. Claims need to be… <ul><li>Specific </li></ul><ul><ul><li>We need a specific definition of the attribute </li></ul></ul><ul><li>Measurable and comparable </li></ul><ul><ul><li>The attribute has to be numerically measureable. </li></ul></ul><ul><ul><li>Comparing two measurements has to be meaningful </li></ul></ul><ul><li>Have a benchmark </li></ul><ul><ul><li>We have to compare our measurement with some value, or </li></ul></ul><ul><ul><li>With another measurement from some other group </li></ul></ul>
  4. 4. Claims: <ul><li>Specific </li></ul><ul><li>Measurable and comparable </li></ul><ul><li>Have a benchmark </li></ul>
  5. 5. Claims: <ul><li>Specific </li></ul><ul><li>Measurable and comparable </li></ul><ul><li>Have a benchmark </li></ul>
  6. 6. Claims: <ul><li>Specific </li></ul><ul><li>Measurable and comparable </li></ul><ul><li>Have a benchmark </li></ul>
  7. 7. Claims: <ul><li>Specific </li></ul><ul><li>Measurable and comparable </li></ul><ul><li>Have a benchmark </li></ul>
  8. 8. Homework <ul><li>Rewrite the following claims so that they are specific, measureable, and comparable with a benchmark etc. </li></ul><ul><ul><li>Most students can access the internet </li></ul></ul><ul><ul><li>Swine flu is dangerous </li></ul></ul><ul><ul><li>Manny Ramirez is a good hitter </li></ul></ul><ul><ul><li>The planet is getting warmer </li></ul></ul><ul><ul><li>Movies starring George Clooney are popular </li></ul></ul><ul><ul><li>A man’s best friend is his dog </li></ul></ul><ul><ul><li>Blondes have more fun </li></ul></ul>
  9. 9. Basic Definitions: Population <ul><li>Population </li></ul><ul><ul><li>The entire group to be studied </li></ul></ul><ul><li>Census </li></ul><ul><ul><li>A collection of data and information from the population </li></ul></ul><ul><li>Parameter </li></ul><ul><ul><li>A numeric measurement or calculation of census data </li></ul></ul><ul><ul><li>Quantifies an attribute of the population </li></ul></ul>
  10. 10. Basic Definitions: Sample <ul><li>Fundamental concept </li></ul><ul><ul><li>A census may not be possible or practical </li></ul></ul><ul><li>Sample </li></ul><ul><ul><li>(Noun) A subset of a population that (we hope) represents the population </li></ul></ul><ul><ul><li>(Verb) The process of collecting data from the subset. </li></ul></ul><ul><li>Statistic </li></ul><ul><ul><li>A numeric measurement or calculation of sample data </li></ul></ul><ul><ul><li>Estimates the parameter of a population </li></ul></ul>
  11. 11. Another Fundamental Concept <ul><li>We are never 100% sure that our sample exactly represents the population </li></ul><ul><li>So a statistic is just an estimate </li></ul><ul><li>We will learn many techniques to deal with this uncertainty </li></ul>
  12. 12. Classifying data <ul><li>Data classification determines the parameters or statistics we can calculate. </li></ul><ul><li>Evaluate the quality of the data </li></ul><ul><ul><li>Does the reported value match the characteristic? </li></ul></ul><ul><ul><li>Does the reported value have the correct precision? </li></ul></ul><ul><li>Three classifications: </li></ul><ul><ul><li>Quantitative or qualitative </li></ul></ul><ul><ul><li>Continuous or discrete </li></ul></ul><ul><ul><li>Nominal, ordinal, interval, or ratio </li></ul></ul>
  13. 13. 1. Classifying Data: Quantitative or qualitative <ul><li>Quantitative </li></ul><ul><ul><li>Measurements or counts </li></ul></ul><ul><li>Qualitative </li></ul><ul><ul><li>Choices </li></ul></ul>
  14. 14. 2. Classifying Data: Discrete or continuous <ul><li>Discrete </li></ul><ul><ul><li>Finite set of values </li></ul></ul><ul><ul><li>Gaps in the sequence </li></ul></ul><ul><ul><li>“ Integer” (Fractions don’t make sense) </li></ul></ul><ul><ul><li>Counts </li></ul></ul><ul><li>Continuous </li></ul><ul><ul><li>Infinite set of values </li></ul></ul><ul><ul><li>“ Decimal” </li></ul></ul><ul><ul><li>Measurements </li></ul></ul>
  15. 15. 3. Classifying Data: Nominal, ordinal, interval, ratio <ul><li>Nominal </li></ul><ul><ul><li>Can not be ordered, or ordering the data doesn’t make sense, except to make it easier to locate </li></ul></ul><ul><ul><li>Example: Favorite color </li></ul></ul><ul><li>Ordinal measurements </li></ul><ul><ul><li>Can be ordered </li></ul></ul><ul><ul><li>The differences between two measurements is meaningless </li></ul></ul><ul><ul><li>Example class rank </li></ul></ul>
  16. 16. Classifying Data <ul><li>Interval measurements </li></ul><ul><ul><li>Measurements can be ordered and the interval between measurements is meaningful </li></ul></ul><ul><ul><li>E.g., temperature </li></ul></ul><ul><li>Ratio measurements </li></ul><ul><ul><li>A zero measurement means ‘none’ </li></ul></ul><ul><ul><li>E.g., Income </li></ul></ul>
  17. 17. For example Measurement Qualitative or quantitative Discrete or continuous Nominal, ordinal, interval, or ratio Approval rating pH Velocity
  18. 18. Homework <ul><li>On-line, go to the web site </li></ul>

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