Correlation and Regression (H1)

What must I take note when drawing a scatter diagram?

• Axes must be labelled

• Regression line must be drawn

• Smallest and largest values of each variable must be indicated

• The points must be relative to each other as seen on the GC

Given that the scatter diagram has a product moment correlation coefficient of 0.9, what can you conclude?

• There is a weak negative linear correlation between x and y

• There is a strong negative linear correlation between x and y

• There is a strong positive linear correlation between x and y

• There is a weak positive linear correlation between x and y

What is/are the limitations of just relying on product moment correlation coefficient ?

(You may choose more than 1 answer)

• The data may not be independent of each other

• There could be non-linear relationship.

• There could be a outlier which affected the value.

• r is not a good indication on strength of linear correlation.

The product moment correlation coefficient between x and y is 0.98.

This means that x direct cause y (or vice versa).

• True

• False

Calculate the product moment correlation coefficient of the data given in the table. Give your answer to 3 significant figures.

The regression line is y = ax+b.

a =

(Give answer to 3 sf)

The equation of the least squares regression line is y = ax + b.

What does a represents?

• Product moment correlation coefficient

• Average change in y per unit change in x

• y-intercept

• Estimated value of x when y=0

For an estimate to be reliable, .......

(choose all that applies)

• r is near to 1 or -1

• it is an extrapolation

• it is an interpolation

• x must be the independent variable.