Correlation Coefficient and Linear Regression Review

Estimate the correlation coefficient for this scatterplot.

• r = 0.56

• r = -0.56

• r = 0.92

• r = -0.92

Which of the following statements is not true of the correlation r between the lengths in inches and weights in pounds of a sample of brook trout?

• r must take a value between -1 and 1.

• r is measured in inches.

• If longer trout tend to also be heavier, then r>0.

• r would not change if we measured the lengths of the trout in centimeters instead of inches.

Which is TRUE?
I.  Random scatter in the residuals indicates a linear model.
II.  If two variables are very strongly associated, then the correlation between them will be near 1 or -1.
III.  Changing the units of measurement for x or y changes the correlation coefficient.

• I only

• II only

• I and II only

• I, II and III

Which is the best CONTEXTUAL description of the y - intercept for the linear regression equation of the rats: Weight = 100 + 40(Time)?

• The y-intercept is 100, which means the rat is predicted to weigh 100 grams at birth. 

• The y-intercept is 100, which is where the graph crosses the y-axis. 

• 100 is where the data starts on the y-axis. 

• The y-intercept is 100, which means at a weight of 0, the rat will take 100 seconds.

What is the correlation coefficient and linear regression of the data set: (1,7) (2,4) (3,-1) (8,-9) (6,-3) (-1,10).

• r = .98 & y = 7.9x - 2.1

• r = .97 & y = 7.9x - 2.1

• r = .95 & y = 7.9x - 2.1

• r = .98 & y = -2.1x + 7.9

• r = .97 & y = -2.1x + 7.9

A linear regression model is run on a set of data.<\/p>

Match the r-value to its description.<\/p>

• weak negative correlation

• -0.97<\/p>

• strong positive correlation

• +0.31<\/p>

• weak positive correlation

• +0.99<\/p>

• weak negative correlation

• -0.44<\/p>

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

The relationship between a, a person’s age, and p, the amount of pets they’ve had, is modeled by the equation p hat= 0.01a + 4.3. Based on the linear regression model, the correlation coefficient could be:

• Between -1 and 0

• Between 0 and 1

• Equal to 0

• Equal to -1

Which value of r represents data with a strong negative linear correlation between two variables?

• -0.86

• -0.50

• 0.89

• 0.07

Find the correlation coefficient (3 sig fgis)