2D Histograms - Advanced Tab

The Advanced tab of the 2D Histograms dialog contains a variety of options for creating 2D histograms.

Variables. Click the Variables button to display the standard variable selection dialog, in which you select the variable(s) to be plotted. When you select more than one variable for a Regular Graph Type, a sequence of graphs is produced (one for each variable). Note that you can select up to 300 variables at one time.

Graph type. Select the type of 2D histogram to be plotted from the Graph type list. Click on the type of the histogram link listed below for a brief description of that type of graph.

Regular	Double-Y
Multiple

Showing Type. Use the Showing Type drop-down box to select the display of your histogram.

Standard. Select Standard to display your graph as a standard 2D histogram.

Hanging Bars. Select Hanging Bars to display your graph as a Hanging Bars histogram.

Cumulative. Select Cumulative in order for the consecutive columns in the resulting histogram to represent cumulative frequencies (i.e., the summation of all preceding categories, up to and including the current category) instead of the raw data.

Stacked. Select Stacked to display your graph as a stacked histogram.

Breaks between columns. Select this check box if you want the histogram columns to be separated from each other. According to common convention, histograms of continuous variables should be displayed with no breaks (the breaks signify discrete values).

Show percentages. Select this check box to display percentages (relative frequencies) at the top of each column in the histogram. Percentages can be displayed for all types of histograms (Regular, Double-Y, Multiple, and Hanging Bars).

Y axis. This box is available only if Regular or Multiple is selected as the Graph Type. You can select different types of labels or scales for the vertical (y) axes in the histogram from the Y axis box. The available options are:

N. If you select N, the histogram will show only the respective frequency counts for the left y-axis labels. Note that you can select the Show percentages check box to display relative frequencies (percentages) at the top of each column in the histogram.

%. If you select %, the histogram will show the respective relative frequency counts (percentages) for the left y-axis labels. This option is available for Multiple histograms only when the variables in the plot have equal N; otherwise a common percentage scale does not exist and the histogram will use the frequency counts to label the y-axis (you can select the Show percentages check box to display percentages at the top of each column in the histogram). Note that the values that will be displayed in the Graph Data Editor window (and that are actually plotted in the histogram) will still be frequency counts; however, appropriate text labels (percentage values) are used as Scale Values for the left y-axis. Therefore, you can easily later change to frequency counts for the y-axis labels. Also note that in order to change the step sizes (increments) for the y-axis, you need to change the respective Step in the Graph Options dialog - Axis: Major Units options pane (to adjust the horizontal grid lines) as well as the Skip values check box in the Graph Options dialog - Axis: Scale Values options pane to display the respective percentage labels at the desired intervals (see the description of Scale Values and Scaling for additional details).

% & N. If you select % & N, the histogram will show the relative frequency counts (percentages) as labels for the left y-axis, and the frequency counts as labels for the right y-axis. Refer to the description of the previous option for a description of percentage labels for the y-axis in histograms (note that, as described in the previous paragraph, this option is available for Multiple histograms only when the variables in the plot have equal N; otherwise a common percentage scale does not exist).

N & %. If you select N & %, the histogram will show the frequency counts as labels for the left y-axis, and the relative frequency counts (percentages) as labels for the right y-axis. This is the reverse labeling as described in the previous paragraph.

Fit type. You can superimpose a distribution over your histogram. Select the type of distribution to fit from this list. For more details on fit types, see Fitted Functions for Histograms.

Intervals. Use the options under Intervals to choose a method of categorization of the values in the histogram for the selected variable(s). Each of the methods is discussed in Method of Categorization and/or Intervals, or click on a link below:

For multivariate histograms (e.g., Double-Y), the categorization is based on the values of the first variable selected in the list. For example, if you first select a grouping variable with two codes (1 and 2), the categorization would be based on those two values of the grouping variable. If you select Integer mode, then the program would scan this grouping variable, select all of the integer values (which in this variable are the values 1 and 2) and base the frequencies of the rest of the selected variables on those integer values.

Statistics. You can include a variety of statistics as footnotes in the graph by selecting one or more of the check boxes under Statistics.

Shapiro-Wilk test. Select this check box to include the Shapiro-Wilk W statistics for normality and its associated p-value.

Descriptive statistics. Select this check box to include a variety of descriptive statistics including the total count, mean, and standard deviation, as well as the minimum and maximum values.

Total count. Select this check box to include the total count or number of cases used in creating the histogram.

Kolmogorov-Smirnov test. Select this check box to include the Kolmogorov-Smirnov d statistics (for normality), its associated p-value, and the Lilliefors statistic.