Scatter Plot

To generate a Scatter Plot of any two quantitative data columns in Grid Data:

1. Select Statistics > Plot Scatter.
2. In the Scatter Plot Parameters dialog:
   1. Select an X Axis Dataset from the drop-down list. Any quantitative Grid Data column can be plotted.
      NOTE: Qualitative data will not be interpreted correctly as numeric data.
   2. Select a Y Axis Dataset from the drop-down list. Any quantitative Grid Data column can be plotted.
   3. Select the Show Regression Line check box to display the best fit linear Regression Line.
   4. Select OK to plot the scatter plot.

The Scatter Plot will be generated. At the bottom of the Scatter Plot, you will see a listing of the Correlation Coefficient, alpha and beta.

Correlation Coefficient

The Correlation Coefficient indicates the degree of correlation between the two variables plotted. The Correlation Coefficient can vary between -1 and 1. Numbers close to zero indicate a poor correlation, and numbers close to 1 or -1 indicate a strong correlation. Note that a negative correlation coefficient simply means that the slope of the best-fit linear regression line is negative.

Alpha and Beta

Alpha and beta represent the y-intercept and slope, respectively, of the best-fit linear regression line to the scatter plot data. The linear regression line can be displayed on the plot by selecting the Show Regression Line option.

Right-Click Options

Several viewing options are available when generating a Scatter plot. These options are available on the Chart menu and/or the right-click menu.

• Regression Line
• Sampler
• Chart Properties
• Copy Chart/Data to Clipboard
• Copy Picture to Clipboard
• Plot in Excel

Regression Line

The Show Regression Line option is only applicable for Scatter Plots and can be used to toggle on or off the display of the best fit linear regression line for a Scatter Plot.

Sampler

The Sampler option on a Scatter Plot allows you to easily determine the coordinates at any point along the plotted values.

1. Right-click on the Scatter Plot, and select the Sampler > Show Sampler option.
2. You will see a dotted cross-hair line on the plot. This is the “Sampler”, and allows you to graphically obtain the coordinates of any point on the scatter plot data.
3. As you move the mouse over the scatter plot data, you will see that the Sampler follows the mouse, and continuously displays the coordinates of points on the scatter plot.