In a polygon map, you may choose to display the values of a single numeric variable using a gradient between two colors.
To change the variable displayed, choose another from the pull-down list below "Use single numeric variable: ".
Graduated color has two modes:
Continuous. For this choice the minimum value will be displayed as the minimum color, and the maximum value as the maximum color, with intermediate values a blending gradient between the two.
Divergent. For this choice, the minimum and maximum values will be displayed as the minimum and maximum colors, both colors will grade into white at the "diverging value" (you can set this in the dialog box). This is the most appropriate display for data where a particular threshold matters.
You also may change the minimum and maximum colors by clicking on the appropriate button (for example, "Min Color") and choosing a new color from the palette.