Bivariate Data

Question 1

What is bivariate data?

Answer 1

When you have data with two variables. Usually one is independent (the explanatory variable) and the other is dependant (the response variable).

Question 2

How do you plot bivariate data on a graph?

Answer 2

The explanatory variable goes on the horizontal axis and the response variable on the vertical.

Question 3

What is a positive correlation and what does it look like on a graph?

Answer 3

As the explanatory variable increases so does the response variable. On a graph the line of best fit (also called the regression line) will go up as you go right.

Question 4

What is a negative correlation and what does it look like on a graph?

Answer 4

As the explanatory variable increases the response variable decreases. On a graph the line of best fit (also called the regression line) will go down as you go right.

Question 5

How do you work out the regression line with your calculator?

Answer 5

Press the menu button then go to statistics and press 2. If frequency is on disable it by pressing setup, going to statistics and turning it off. Fill in the table with all the points and then press options and then 4.

Question 6

What does r mean on the answer screen for the regression line?

Answer 6

r is the correlation coefficient. If this is positive there is a positive correlation, if it is negative, there is a negative correlation and if it is equal to 0 there is no correlation.

Question 7

What is the regression line?

Answer 7

The line of best fit. It is written as y=a+bx where a and b are constants.