Scatter Plots (also called scatter diagrams) are used to investigate the possible relationship between two variables that both relate to the same "event." A straight line of best fit (using the least squares method) is often included.
Things to look for:
There is a maxim in statistics that says, "Correlation does not imply causality." In other words, your scatter plot may show that a relationship exists, but it does not and cannot prove that one variable is causing the other. There could be a third factor involved which is causing both, some other systemic cause, or the apparent relationship could just be a fluke. Nevertheless, the scatter plot can give you a clue that two things might be related, and if so, how they move together.
For scatter plots, the following statistics are calculated:
|Mean X and Y:||the average of all the data points in the series.|
|Maximum X and Y:||the maximum value in the series.|
|Minimum X and Y||the minimum value in the series.|
|Sample Size||the number of values in the series.|
|X Range and Y Range||the maximum value minus the minimum value.|
|Standard Deviations for X and Y values||Indicates how widely data is spread around the mean.|
|Line of Best Fit - Slope||The slope of the line which fits the data most closely (generally using the least squares method).|
|Line of Best Fit - Y Intercept||The point at which the line of best fit crosses the Y axis.|