Linear Correlations

Which of the following variables is used to represent the correlation?

• C

• n

• S_x

• r

What is the direction of the scatter plot?

• Positive Association

• Negative Association

• None

• Linear

A line of regression has the formula:

y = 2.5x + 5.

Find the residual of the point (4 , 8).

• 7

• -7

• 17

• -17

r = 0.599. What is the strength of the correlation?

• Strong

• Weak

• Moderate

• None

• y = 3.9x - 53.5

• y = 0.2x + 2

• y = 0.2x + 8

• y = 3.9x + 53.5

Which of the following is the formula for finding the residual?

• predicted y- observed y

• observed y- predicted x

• predicted x - observed x

• observed y - predicted y

Correlation coefficient is the statistic that measures the strength and direction of a linear association between two quantitative variables.

• True

• False

If r is positive, then there is...

• Negative association

• No correlation

• Positive association

If r=0 , then there is...

• Negative association

• No correlation

• Positive association

Which of the following statements is true?

• The correlation coefficient and the slope of the regression line may have opposite signs.

• A correlation of 1 indicates a strong relationship between the variables.

• Correlations of +0.87 and -0.87 indicate the same degree of clustering around the regression line.

• A correlation of 0 shows little or no association between two variables.