Statistics Chapter 3b

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Author:
honestkyle
ID:
198125
Filename:
Statistics Chapter 3b
Updated:
2013-04-11 12:17:03
Tags:
deviation variance coefficient stats
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Description:
Standard deviation and variance calculations. Things are getting more difficult.
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  1. What are z-scores often called?
    Standardized scores
  2. What can a z-score tell you?
    How many standard deviations a value is from the mean
  3. What is the z-score equation?
  4. What is the mean of a z-score?
    0
  5. What is the standard deviation of a z-score?
    1
  6. What does the +/- mean terms of z-scores?
    • + value means how many standard deviations ABOVE the mean
    • - value means how many standard deviations BELOW the mean
  7. What does the Empirical rule apply to?
    • Data that is "normally distributed"
    • Example: skewness = 0, mean median
  8. What are the 3 parts to the Empirical rule?
    • 68% of the values will be between z = -1 and z = +1
    • 95% of the values will be between z = -2 and z = +2
    • 99.7% of the values will be between z = -3 and z = +3
  9. What are outliers?
    Unusually small or large values in a dataset
  10. What z-scores do outliers typically have?
    z < -3 or z > +3
  11. What could be the cause of an outlier?
    • Error
    • Evidence of something unusual
  12. What does covariance measure?
    Linear associate between 2 variables
  13. What is the covariance equation for a sample statistic?
  14. What is the covariance equation for a population parameter?
  15. For a covariance, what does the sign tell you?
    • Positive = direct relationship
    • Negative = inverse relationship
  16. For a covariance, what does the value tell you?
    Nothing
  17. What is the correlation coefficient equation for a sample statistic?
  18. What is the correlation coefficient equation for a population parameter?
  19. What does the correlation coefficient measure?
    The strength of the relationship
  20. How strong is the relationship for two variables with a correlation coefficient of .30?
    Weak
  21. How strong is the relationship for two variables with a correlation coefficient of .50?
    Moderate
  22. How strong is the relationship for two variables with a correlation coefficient of .80?
    Strong
  23. How strong is the relationship for two variables with a correlation coefficient of .90?
    Very strong

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