2D/3D Graphs - Options 2 Tab

Graphical Analytic Techniques

Select the Options 2 tab in the graph specification dialog of any 2D or 3D graph accessed from the Graphs menu except Graphs of Block Data and Graphs of Input Data, which use default options. Use the options on this tab to set up the graph layout and make choices relevant to the fitted function. Additional options are available to use random subsampling of cases in computing the graph, to monitor (or not to monitor) the progress of graph creation via a progress bar, and to add the respective graph to the Graph menu as a user-defined graph. Note, however, that some of these options are not applicable to all graph types. For example, 3D plots cannot use polar coordinates (see below).

Graph layout. The options in the Graph layout group box are used to select the desired coordinate system and the axes positions in displaying the graph.

Coordinate system. Use the Coordinate system box to select a coordinate system to use with 2D graphs. Select Standard (Cartesian) to use standard X vs. Y (Cartesian) coordinates. Select Polar to convert the X-Y data to polar coordinates based on r and θ (theta). In the polar coordinate system, r represents the distance from the polar axis (center of the circle) along a straight line and θ represents the angle of the straight line measured in radians.

Polar plots are automatically scaled from 0 to 2π (pi) radians and are circular in appearance, with the X variable plotted around the circumference and the Y variable plotted radially. Polar coordinates are not an available option for 3D and some other graph types.

X-Y Axis position. Use the X-Y Axis position box to specify the position of X and Y variables (selected on the Quick or Advanced tab) on the x- and y-axes of the graph. Select Standard and the values for the selected X variable will be displayed along the (horizontal) x-axis in the 2D plot, and the values for the selected Y variable will be displayed along the y-axis (i.e., the vertical axis in 2D plots). Select Reversed to display the values for the selected X variable along the y-axis, and the values for the selected Y variable along the x-axis. This option is not applicable to 3D plots.

Fitted function. The options in the Fitted function group box are used to control some important characteristics of the fitted 2D function, such as display of the fitted function expression, degree of the polynomial for a polynomial fit, and the logarithmic base to be used in fitting logarithmic 2D functions.

Display fit expression. Use the Display fit expression box to control the display of the fitted function(s)/equation(s) expressions in the graph. Select In title from the drop-box to display the fit expressions in the title area of the graph. Select Custom text to display the fit expressions as a movable legend in the graph. Selecting Custom text will force the text of the fit expressions into the custom (movable) text format, even if the number of functions/equations is less than 5 and thus they would fit in the fixed title area of the graph. This option is useful when you intend to extensively edit or integrate the text of functions/equations with other text or when the lengths of the functions/equations exceed the capacity of the fixed title area. Note that if there are more fit expressions than can be accommodated in the fixed title area of the graph, they will be displayed as custom text. This option can be set globally in the Analyses/Graphs: Display options pane of the Options dialog, accessible by selecting Options from the Tools menu.

Polynomial Order. Use the Polynomial Order box to select the polynomial order for the polynomial fit, if one is chosen for the current (2D) graph. You can choose Quadratic (2nd order), Cubic (3rd order), Quartic (4th order), or Quintic (5th order). The selected order can be changed after the graph is created.

Logarithm base. Use the Logarithm base box to select either the natural log (base e) (select Euler) or base 10 (select 10) for the fitted logarithmic function in the graph; the setting of this option will not affect the computations if the chosen fit is not Logarithmic.

Display Progress Bar. Use the Display Progress Bar box to enable or disable the red progress bar on the status bar during graph creation. You can choose to display the progress bar each time a graph is created (select Enable) or to turn off the display of the progress bar (select Disable).

Sampling. Use the options in this group box to create a graph based on a sub-sample of observations in the current data file.

Enable. Select this check box to enable random subsampling of cases (observations).

Approximate number of cases. Select the Approximate number of cases option button and in the corresponding edit field, enter the approximate number of cases to be used when creating the subset.

Approximate percent of cases. Select the Approximate percent of cases option button, and in the corresponding edit field, enter the approximate percentage of cases to be used when creating the subset.

Add as User-defined Graph to Menu. If you intend to repeatedly use the current graph, you may want to save the selections used in creating this graph so that they are readily available for future use. This option is used to save the current selections as a user-defined graph with the specified name that will be displayed in the Graphs - User-defined Graphs menu. When you click the Add as User-Defined Graph to Menu button, the New User-Defined Graph dialog is displayed in which you specify the menu name of the graph you want to save. If you also want to save the variables that were used in creating this graph, select the Save variables check box on this dialog.