# Statistics Chapter 3b

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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
 Author: honestkyle ID: 198125 Card Set: Statistics Chapter 3b Updated: 2013-04-11 16:17:03 Tags: deviation variance coefficient stats Folders: Description: Standard deviation and variance calculations. Things are getting more difficult. Show Answers: