Regression Lines and Correlation

The correlation coefficient of the regression line is 0.986. What does that mean?

• There is a very strong, positive correlation between the variables.

• There is a very strong, negative correlation between the variables.

• There is a weak, negative correlation between the variables.

• As fork length increases, so does total length.

What does a y-intercept of 4.1 mean?

• A shark with fork length of 0cm, will have a total length of 4.1cm.

• For each cm the shark get's longer, it's forklength increases by 1.1cm.

• For each 1cm increase in forklength, a shark gets 1cm longer.

• A shark if longer that it's fork length.

What is missing from this graph?

• suitable title

• units of x and y axis

• regression line

• all of these

What is the gradient of the regression line?

• 1.1

• 2527

• total length (cm) = 1.1forklength (cm) + 4.1

• 4.1

Using the regression equation: length (cm) = 1.1 forklength (cm) + 4.1 Predict the length of a shark with a fork length of 4cm.

• 4.1cm

• 4.4cm

• 8.5cm

• 5.2cm

Using the regression equation: length (cm) = 1.1 forklength (cm) + 4.1

Predict the length of a shark with a fork length of 40cm.

• 41cm

• 48.1cm

• 56.1cm

• 44.1cm

What does a gradient of 1.1 mean?

• Sharks grow in 1.1cm bursts

• For each cm the shark get's longer, it's forklength increases by 1.1cm.

• For each 1cm increase in forklength, a shark gets 1.1cm longer.

• A shark if longer that it's fork length.

How many sharks were in the sample?

• 0.986

• 1.1

• 4.1

• 2527

Using the regression equation: length (cm) = 1.1 forklength (cm) + 4.1

Predict the length of a shark with a fork length of 10cm.

• 14.1cm

• 14.4cm

• 15.5cm

• 15.1cm

If the point with the red x is removed from the scatterplot, what will happen to the slope of the LSRL and the correlation coefficient?

• slope increases, r increases

• slope decreases, r increases

• slope increases, r decreases

• slope decreases, r decreases

• slope is unchanged, r increases