Correlation

The correlation coefficient is a number "r" such that: 

• -1<r<1
• -1>r>1
• -1≤r≤1
• -1≥r≤1

What type of association does this graph have?

• positive 
• negative
• none
• all of the above

Describe the following correlation coefficient:

r = -0.89

• Strong positive 
• Weak positive 
• Strong negative 
• Weak negative 

Estimate the correlation coefficient

• r = 1

• r = -1

• r ≈ -0.8

• r ≈ 0.8

• r ≈ -0.5

What type of correlation (association)?

The outside temperature and the amount of layers you wear.

• A) Positive correlation

• B) Negative correlation

• D) No correlation

Which value below could be the correlation of the scatterplot?

• -0.923

• -0.478

• 0.006

• 0.777

As x increases, y decreases.

• A) no correlation

• B) negative correlation

• C) correlation coefficient

• D) positive correlation

Determine the Correlation Coefficient and decide whether it is weak, moderate, or strong.

• 0.07 weak
• -0.26 weak
• -0.26 moderate
• 0.07 strong

Given that the scatter diagram has a product moment correlation coefficient of 0.9, what can you conclude?

• There is a weak negative linear correlation between x and y

• There is a strong negative linear correlation between x and y

• There is a strong positive linear correlation between x and y

• There is a weak positive linear correlation between x and y

r is only useful for ...

• Quadratic functions

• Linear functions