Means with Error Plots - Quick Tab

Select the type of Mean with Error Plot to be plotted from the Graph type list. Click the desired plot link listed below to obtain a brief description of that type of graph.

Whiskers

High-Low Close

Columns

You can also choose between two types of graph formats. Click the desired graph format link listed below to learn more about it.

Regular

Multiple

The choice of the combination of the Graph type and format will depend on the objective you have in mind. For example, if you have selected more than one dependent variable and your aim is to compare their distributions, then you may select Whiskers with Multiple graph format.

Click the Variables button to display a standard variable selection dialog box, in which you select the Dependent variable and the Grouping variable for creating the graph.

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 more than one dependent variable can be selected and selection of the Grouping variable is optional. If you select multiple dependent variables and the Regular graph format (see above), a sequence of Means with Error Plots (one for each dependent variable) will be produced in separate graphs. If the graph Format is set to Multiple, then the Means with Error Plots for all the selected dependent variables will be combined into a single graph. The selection of variables that you make will be displayed in the area of the dialog box below the Variables button.

Use the options under Grouping intervals to select a method  (Integer mode, Unique Values, 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.

The graph icon displayed 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.

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

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.

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.

The options under Whisker are used to specify the range of Whiskers or High-Low Close, i.e., to define the error ranges.

Use these options to specify how the range of Whiskers or High-Low Close are computed (Std def, Std error, Conf. Interval, Non-outlier range, Min-max, or Constant).

When you select Std dev, the specified constant will be multiplied by the standard deviation of the plot data and added/subtracted from the chosen center point to define the range.

When you select Std error, the specified constant will be multiplied by the standard error of the plot data and added/subtracted from the chosen center point to define the range.

When you select Conf. Interval, the range will be displayed as the confidence interval around the mean value.

When you select Non-outlier range, 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.

Alternatively, 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.

When you select Constant, the specified constant will be added/subtracted from the chosen center point (mean or median), to define the range around that center point.

If you specify the Value option (see above) as Conf. Interval, 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.

Frequency / severity plot. When this check box is selected, a line of means is overlaid on the histogram. The line doesn't show raw values, but is relative to the mean in the most frequent category. Note that this option is not available for multiple plots or when no grouping variable is selected.