Correlation

Which of the following best defines correlation?

• A statistical index of the direction and strength of a relationship between two variables

• method that shows one variable causes another

• A statistic used only when there are more than three variables

• A statistic used only when there are more than three variables

• A formula that always produces values greater than 1

Two variables can have a strong correlation without one causing the other

• • True

• • False

Which of the following represents the weakest correlation?

• -0.75

• +0.05

• +0.62

• -0.48

When exploring the relationship between study hours and exam grades, which graph is most appropriate?

• Scatterplot

• Line graph

• Pie chart

• Histogram

Look at the scatterplot. What type of correlation does it most likely show?

• Linear, moderate, positive correlation

• Linear, strong, positive correlation

• Linear, moderate, negative correlation

• No correlation

The values of Pearson’s r can never be outside which range?

• -1 to +1

• -2 to +2

• no limit

• 0 to +10

Which statement about linear regression is correct?

• It always proves causation

• It fits a straight line to data to help with prediction

• It only works when r = +1

• It is used only for categorical variables

A correlation of -0.72 indicates a stronger relationship than +0.41.

• • True

• • False

In the regression equation y = bx + a, the intercept is represented by:

• X

• Y

• B

• A

Look at the scatterplot, with a regression line (red) and vertical distances drawn from the points to the line. What is the correct name for these vertical distances?

• Coefficient

• Confound

• Residual

• Variable