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honestkyle
on FreezingBlue Flashcards.
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What are z-scores often called?
Standardized scores
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What can a z-score tell you?
How many standard deviations a value is from the mean
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What is the z-score equation?
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What is the mean of a z-score?
0
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What is the standard deviation of a z-score?
1
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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
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What does the Empirical rule apply to?
- Data that is "normally distributed"
- Example: skewness = 0, mean
 median
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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
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What are outliers?
Unusually small or large values in a dataset
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What z-scores do outliers typically have?
z < -3 or z > +3
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What could be the cause of an outlier?
- Error
- Evidence of something unusual
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What does covariance measure?
Linear associate between 2 variables
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What is the covariance equation for a sample statistic?
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What is the covariance equation for a population parameter?
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For a covariance, what does the sign tell you?
- Positive = direct relationship
- Negative = inverse relationship
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For a covariance, what does the value tell you?
Nothing
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What is the correlation coefficient equation for a sample statistic?
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What is the correlation coefficient equation for a population parameter?
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What does the correlation coefficient measure?
The strength of the relationship
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How strong is the relationship for two variables with a correlation coefficient of .30?
Weak
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How strong is the relationship for two variables with a correlation coefficient of .50?
Moderate
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How strong is the relationship for two variables with a correlation coefficient of .80?
Strong
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How strong is the relationship for two variables with a correlation coefficient of .90?
Very strong
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