AP Statistics : How to find correlation
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Example Questions
Example Question #1 : Bivariate Data
Which of the following correlation coefficients indicates the strongest relationship between variables?
Correlation coefficients range from 1 to -1. The closer to either extreme, the stronger the relationship. The closer to 0, the weaker the relationship.
Example Question #2 : Bivariate Data
It is found that there is a correlation of exactly 
Correlation is measured on a scale of 
There is a strong association between the two variables.
There is enough evidence, with a correlation of 
All of the answer choices are correct
The association between the two variables is positive
There is enough evidence, with a correlation of
Under no circumstance will correlation ever equate to causation, regardless of how strong the correlation between two variables is. In this case, all other answer choices are correct.
Example Question #1 : How To Find Correlation
In a medical school, it is found that there is a correlation of 
i. There is a positive association between the two variables.
ii. There is a strong correlation between the two variables.
iii. Coffee consumption in medical school students causes students to sleep less each night.
iii only
i and ii
i, ii, and iii
i and iii
ii only
ii only
Since the correlation is negative, there must be a negative association between the two variables (therefore statement i is incorrect). Statement ii is correct since a correlation of 
Example Question #1 : How To Find Correlation
Which of the following shows the least correlation between two variables?
The strength of correlation is measured on an absolute value scale of 
A correlation of 
Example Question #1 : How To Find Correlation
Which of the following correlation coefficients implies the strongest relationship between variables:
A high correlation coefficient regardless of sign implies a stronger relationship. In this case 
Example Question #2 : Bivariate Data
A national study on cell phone use found the following correlations:
-The correlation between the number of texts sent each day and a person's average credit card debt is 
-The correlation between the number of texts sent each day and the number of books read each month is 
Which of the following statements are true?
i. As the number of texts sent each day increases, average credit card debt increases.
ii. Sending more texts causes people to read less.
iii. A person's average credit card debt is related more strongly to the number of texts sent each day than the number of books read each month is related to the number of texts sent each day.
ii
iii
i and iii
ii and iii
i and ii
i and iii
i is correct because there is a positive correlation between the number of texts sent each day and average credit card debt.
ii is incorrect because the word "cause" was used in the statement. Correlation does not mean causation. There is a relationship between the number of texts sent each day and the number of books that a person reads each month. However, the number of texts sent each day does not cause a person to read a certain number of books each month.
iii is correct because the absolute values of the correlations indicate which correlation is stronger. 
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