Lines of Best, Correlation Coefficients and Residuals

The scatter plot shows the number coffee shops in different cities and the number of violent crimes. Which of the following is NOT true?

• A) As the number of coffee shops increase, violent crimes appears to increase.

• B) The line of best fit (regression line) shows a positive correlation

• C) The data has a positive correlation coefficient

• D) An increase in coffee shops causes an increase in violent crimes

• Positive, strong
• Positive, weak
• Zero
• Negative, strong

Rank these scatter plots according to the intensity of the correlation represented, from weakest to strongest.

• 1, 2, 3, 4
• 2, 4, 3, 1
• 4, 3, 2, 1
• 1, 3, 4, 2

How do you calculate a residual?

• Observed - Predicted
• Predicted - Observed

Residuals are . . . 

• possible models not explored by the researcher
• variation in the response variable that is explained by the model
• the difference between the observed response and the values predicted by the model
• data collected from individuals that is not consistent with the rest of the group

Estimate the correlation coefficient.

• r = -0.8
• r = -0.5
• r = 0.5
• r = 0.8

Estimate the correlation coefficient for this scatterplot.

• r = 1.2
• r = 0.89
• r = 0
• r = -0.89

The correlation coefficient r is a value between

• 0 and 1
• 0 and 100
• -1 and 1
• -2 and 2

What type of correlation exists between the number of people that go to the pool and the temperature outside.

• positive
• negative
• no correlation
• unknown

What type of correlation exists between the temperature outside and the number of hot chocolate sold at a football game.

• positive
• negative 
• no correlation
• unknown