In this session, we will discuss axes and grid lines in NCSS plots. We will use the scatter plot format window as an example representing other NCSS plots with axes and grid lines. The scatter plot format window is opened by clicking the plot format button of the scatter plots procedure, or, on the plots tab of any other procedures that provide a scatter plot, such as the regression procedures.
We will use the Y axis as an example. The numeric axis is the comparable axis in some of the other plot format windows. In many of the plots there is a group axis in addition to a numeric axis. The principles outlined below generally apply to those axes as well. The default setting for the minimum and maximum boundary is ‘blank’. When these boundaries are blank, NCSS uses an algorithm to determine a suitable minimum or maximum based on the data involved. You can set a specific boundary for the minimum or maximum or both if you wish. The ‘Corners’ button is used to give axes a small shift, which, in effect, removes the sharp corners of the graph. This feature may also be useful when points are right on one of the axes.
The axis scale may be set to linear or log. The log scale number format can be shown as numbers or as powers of the base. There are two lines for each numeric axis, one for each side of the graph. The format of these lines is specified by using the drop-down of quick line format choices, or using the custom line format window. By default, these lines are located at the ends of the adjacent axis, but a specific value can be entered for their location. The lines can be further adjusted by setting a minimum or maximum for the visible part of the line of the axis. Working in tandem with the specification of the ticks can give a very specialized axis.
The tick marks and tick labels can independently be included or excluded from either side of the graph. The tick marks format button allows you to specify the fill, size, and position of the tick marks. The ‘Tick Number and Spacing’ button gives several ways to specify the location of the major and minor ticks along the axis. The number and interval options are used in conjunction with the Min and the Max values. The ‘List’ option provides a way to directly enter tick locations. The minor tick section will be grayed out if no minor ticks checkboxes are checked.
The tick labels have buttons to specify the text font, the layout, and the number format of the tick labels. The grid line locations follow the locations of the major and minor ticks. Individual grid lines or a custom series of grid lines may also be specified at custom locations. This concludes our discussion of the axes and grid lines in NCSS plots.