Scatter plots
Scatter plots are used to show relationship between two sets of data by writing them as ordered pairs
To illustrate, let us pretend that you have a business that sells notebooks
Day 1, you sell 10 notebooks
Day 1, you sell 10 notebooks
Day 2, you sell 5 notebooks
Day 3, you sell 15 notebooks
Day 4, you sell 10 notebooks
Day5 , you sell 20 notebooks
Day 6, you sell 15 notebooks
Day 7, you sell 30 notebooks
Day 8, you sell 15 notebooks
Day 9, you sell 25 notebooks
Day 10, you sell 15 notebooks
You can display this situation with ordered pairs as shown below:
(1,10), (2,5), (3,15), (4,10), (5,20), (6,15), (7,30), (8,15), (9, 25), and (10, 15)
Then we can put the ordered pairs on the coordinate system. The resulting graph is called a scatter plot or scatter graph.
Notice how the points are scattered around and everything is located in the first quadrant
Two sets of data can form 3 types of relationships
When y increases as x increases, the two sets of data have a
positive correlation
Basically, when you closely examine the graph, you will see that the graph has a tendency to go upward
Example
When y decreases as x increases, the two sets of data have a
negative correlation
Basically, when you closely examine the graph, you will see that the graph has a tendency to go downward
Example
When x and y are not related, we say that the two sets of data have no correlation
Example