Plot: Box/Whisker

Double-click in the background of a graph to display the Graph Options dialog box. Select Box/Whisker, located under Plot, to access the options described here, which are used to define the statistics that are indicated by the components of each box-whisker combination in box and whisker type plots, as well as some of the characteristics of the plotted box/whiskers. The method of categorization for categorized box and whisker plots can also be specified on the Plot: Box/Whisker tab. These options are available in the Box/Whisker dialog box as well as in the Graph Options dialog box - Plot: Box/Whisker tab.

Plot. Use the Plot drop-down box to select the plot to which you want to make changes. If you have several plots in one graph, you can assign names to each plot using the Name field on the Plot: General tab.

Statistics. Click the Statistics button to display the Statistics dialog box for box-whisker type plots, in which you can select a variety of statistics that will be included in your graph. You can select the nonparametric Kruskal-Wallis test (see also Nonparametric Statistics) and the ANOVA F test (see, for example, General ANOVA/MANOVA). Note that if you do select statistic(s) to include in your graph, the Add Legend dialog box will also be displayed, which is used to select where and how to attach the statistic(s) to the graph. Statistics will not be calculated for graphs that do not involve categorization within variables (e.g., for box and box and whisker plots for multiple variables without categorization, or plots from blocks of data).

Type. The Type group contains options to further define the plot.

Middle point. Use the Middle point drop-down box to select the statistic Mean or Median to be used to determine the center (middle) points in the plot (variable and group). Note that the specific method used to compute the Medians (and percentiles) can be configured for all functions and statistical analyses in the Options dialog box - Analyses/Graphs: Limits tab. For more information, see Percentile Calculation Options in STATISTICA.

Pooled Variance. The setting of the Pooled Variance check box determines how the standard deviations and standard errors (for the means) are computed from grouped data. When the Pooled Variance check box is selected, STATISTICA computes the pooled within-group (category) variance for all groups (categories), and uses this value as an estimate of σ (Sigma) in computing the standard errors for the means. For more details on this option see the description of the Pooled Variance check box on the Means with Error Plots dialog box - Advanced tab. Note that this check box is only available when you select Mean as the Middle point.

More. Click the More button to display the Box/Whiskers More Options dialog box, in which you can select additional options to compute the box and whiskers, control the display of outliers and extremes, and use the trimmed distribution of the dependent variable to compute mean/median. This option is not available when the Scatterplot with error bars check box is selected.

Box value. Use the Box value drop-down box to assign a statistic to the box drawn in the box and whisker plot. The options available depend on the Middle point you selected. For the Median, you can select Percentiles, Min-Max, and Constant (draw a box to enclose a fixed-value interval around the middle point); for the Mean Middle point, you can select Std. Dev. (standard deviation), Std. Err. (standard error of the mean), Conf. Interval (confidence interval for the mean), Min-Max (minimum and maximum value of the dependent variable), and Constant. For additional specifications (e.g., to set the specific percentiles, percent value for the confidence intervals, constant, etc.) click the More button to display the Box/Whiskers More Options dialog box. The specific method used to compute the percentiles can be configured for all functions and statistical analyses in the Options dialog box - Analyses/Graphs: Limits tab. For more information, see Percentile Calculation Options in STATISTICA.

Whisker value. Use the Whisker value drop-down box to choose how the ranges of Whiskers are computed; the options available in this box depend on the Middle point you selected. For the Median middle point, the available choices include Percentiles, Non-outlier range (see Outliers), Min-Max (minimum and maximum values), and Constant (draw the whiskers to enclose a fixed-value interval around the middle point). For the Mean middle point, available options are Std. Dev. (standard deviation), Std. Err. (standard error of the mean), Conf. Interval (confidence interval for the mean), Non-outlier range (see Outliers), Min-Max (minimum and maximum value), and Constant. For additional specifications (e.g., to set the specific percentiles, percent value for the confidence interval, constant, etc.) click the More button to display the Box/Whiskers More Options dialog box. The specific method used to compute the percentiles can be configured for all functions and statistical analyses in the Options dialog box - Analyses/Graphs: Limits tab. For more information, see Percentile Calculation Options in STATISTICA.

Scatterplot with error bars. Select this check box to specify that, when the OK button is clicked, error bars will be generated in the plot for all x-axis values that have more than one y-value associated with them. Note that when this check box is selected, the More option, the options in the Intervals group, the Intervals value format option, and the Scale X option become unavailable.

Intervals. Use the options in the Intervals group to select a method (Integer mode, Unique values, Categories, Boundaries, Codes, or Multiple subsets) to define the manner in which the values in the chosen grouping variable will be used to determine the categories for the graph. Note that separate means (medians, etc., as specified on this tab) 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.

Change Variable/Specify Boundaries/Specify Codes/Specify Subsets. Note that the name of this button changes depending on the Interval option button that is selected. Click the Change Variable button to display a standard variable selection dialog box, which is used to change the selection of the grouping variable to which the Intervals options apply. Click the Specify Boundaries/Codes/Subsets button to display various dialog boxes in which you enter the boundaries, codes, or subsets that are used to create user-defined categories.

Properties. The options in the Properties group are used to specify various aspects (sizes, etc.) of the components of the box/whiskers.

Intervals value format. Click the Intervals value format button to display the Value Format dialog box; the display format chosen in that dialog box will be used to label the horizontal (by default) axis in the plot, along which multiple box/whiskers are plotted. See also the Intervals group for the different ways in which the data can be categorized.