Categorized Means with Error Plots - Quick Tab

Graphical Analytic Techniques

Select the Quick tab of the Categorized Means with Error Plots dialog to access options to specify the variables, select the type of Mean with Error Plot (Whiskers or High-Low Close) you want to create, and select various options regarding the graph. More options are available on the Advanced tab of this dialog.

Graph type. Select the type of Mean with Error Plot to be plotted from the Graph Type box on this tab. Click the desired plot link below to obtain a brief description of that type of graph.

Layout. Select the type of layout for the graph(s).

Separate. Select this option button to produce a Separate plot layout (where each subset of cases is displayed in a separate graph) for the categorized plots.

Overlaid. Select this option button to produce an Overlaid plot layout (where all subsets are overlaid in one graph and identified by patterns and colors) for the categorized plots.

Variables. Click the Variables button to display a standard variable selection dialog in which you can select the Dependent variable, the Grouping variable, and the X- and (optional) Y-Category variables for creating the graph. If more than one dependent variable is selected, then a sequence of graphs (one for each dependent variable) will be produced using the same set of grouping variables. The selection that you make will then be displayed in the area of the dialog below the Variables button.

The dependent variable values will be used in calculating the respective statistics that define the components of the graph (e.g., means, medians, standard deviations, etc.), while the grouping variable will be used to categorize the data, using the method of categorization as selected via the options in the Grouping intervals group. Note that the selected grouping variables do not have to be categorical variables (e.g., contain codes); you can use one of the methods of categorization to categorize continuous variables. The selection of grouping variables is not necessary if the categories are defined via the Multiple Subsets method on the Advanced tab.

Graph icon. The graph icon in the lower section, left side of the Quick tab represents the currently selected Graph type (Whiskers or High-Low Close) and the Mean. It also previews the selected Value (Conf. Interval, Non-outlier range, Min-max, or Constant) that will define the Mean with Error Plot that you are about to create as specified in the Whisker group box.

Whisker. The options in the Whisker group box are used to select the options for computing the range of Whiskers or High-Low Close, i.e., to define the error ranges.

Value. Use the Value drop-down box to choose how the range of Whiskers or High-Low Close are computed (Conf. Interval, Non-outlier range, Min-max, or Constant). If you select Conf. Interval, then the range will be displayed as the confidence interval around the mean value. If you select Non-outlier range, then STATISTICA determines which points in the data are outliers (see Outliers and Extremes), and then uses the highest and lowest data points that are closest to the outliers (but are not outliers) to determine the range in the plot. On the other hand, the option Min-Max uses the minimum and maximum values of the data to determine the range, without considering whether or not these values are outliers. If you choose option Constant, then the specified constant will be added/subtracted from the chosen center point (mean or median), to define the range around that center point.  

Probability/Coefficient. If you select the Value option (see above) as Conf. Interval, then you also need to specify a value between 0.15 and .99 in the Probability edit field. This value will be used to determine the length of the Whiskers or High-Low Close around the Mean value, based on the standard error for the respective means, and the standard normal (z) value associated with the chosen probability. When you select the Value as Non-outlier range or Min-max (see above), you also need to specify a value in the Coefficient edit field by which the selected Value will be multiplied to determine the range. In case of the Value option as Constant, the value of the Coefficient itself determines the range (no multiplier is used). By default the value of the Coefficient is 1.

Grouping intervals. Use the options in the Grouping intervals group box to select a method (Integer mode, Unique Values mode, Categories, or Codes ) to define the manner in which the values in the chosen grouping variable will be used to determine the categories for the graph; additional options are available on the Means with Error Plots - Advanced tab. Note that separate means (medians, etc., as chosen by the user) will be computed for each group as defined by the values in the grouping variable. The methods for categorizing the values in the grouping variable are discussed in detail in Methods of Categorization.