A graph of plotted points that show the relationship between two sets of data.
In this example, each dot represents one person's weight versus their height.
(The data is plotted on the graph as "Cartesian (x,y) Coordinates")
The local ice cream shop keeps track of how much ice cream they sell versus the temperature on that day. Here are their figures for the last 12 days:
|Ice Cream Sales vs Temperature|
|Temperature °C||Ice Cream Sales|
And here is the same data as a Scatter Plot:
It is now easy to see that warmer weather leads to more sales, but the relationship is not perfect.
Line of Best Fit
You can also draw a "Line of Best Fit" (also called a "Trend Line") on your scatter plot:
Try to have the line as close as possible to all points, and as many points above the line as below.
Example: Sea Level Rise
A Scatter Plot of Sea Level Rise:
|And here I have drawn on a "Line of Best Fit".|
When the two sets of data are strongly linked together we say they have a High Correlation.
The word Correlation is made of Co- (meaning "together"), and Relation
- Correlation is Positive when the values increase together, and
- Correlation is Negative when one value decreases as the other increases
(Learn More About Correlation)
Correlations can be negative, which means there is a correlation but one value goes down as the other value increases.
Example : Birth Rate vs Income
The birth rate tends to be lower in richer countries.
Below is a scatter plot for about 100 different countries.
It has a negative correlation (the line slopes down)
Note: I tried to fit a straight line to the data, but maybe a curve would work better, what do you think?