| Variables
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Click this button to display a 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 box.
Note: 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 type (see below), a sequence of Means with Error Plots (one for each dependent variable) will be produced in separate graphs. If the graph type is set to
Multiple, the Means with Error Plots for all the selected dependent variables will be combined into a single graph. A list of the selected variables is displayed below the
Variables button.
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| Graph type
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Select the type of graph to be plotted from this list. Click a link below for a brief description of that type of graph.
 Whiskers
 High-Low Close
Together with the
Graph type selected above, you can also choose between two types of graph formats. Click a link below to learn more about the format.
 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, you may select
Whiskers with
Multiple graph format.
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| Grouping intervals
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Use the options in this group box to specify a method (Integer mode, Unique values, Boundaries, Categories, 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 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.
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| Change Variable
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Click this button to display a standard variable selection dialog box in which you can change the selection of the
Dependent variable(s) and/or the
Grouping variable.
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| Fit type
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You can fit an equation to the points in the plots by selecting one of the predefined functions in this list (or select
Off).
 Linear
 Polynomial
 Logarithmic
 Exponential
 Distance Weighted Least Squares
 Negative Exponential Weighted
 Spline
 Lowess
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| Graph icon
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The graph icon displayed represents the currently selected
Graph type (Whiskers or
High-Low Close) and the
Middle point options (see below). 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.
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| Middle point
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The options in this group box are used to specify the statistic that will be used as middle point in the Means with Error Plots.
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| Value
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The middle point can be either the
Mean,
Median,
Mean/Median (uses the Mean as the middle point, plus it has an added marker for the Median), or
Median/Mean (uses the Median as the middle point, plus it has an added marker for the Mean) of the selected variable.
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| Style
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Use this drop-down list to specify how the middle point should be represented in the
Whiskers or
High-Low Close plot. You can choose the selected middle point to appear as
Line or as a
Point.
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| Pooled variance
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This check box is available when
Mean is selected as the
Middle point value. The setting of this 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 (see, for example, Milliken and Johnson, 1984). Specifically, Statistica computes the pooled within-group (category) variance as:
spooled2 = 1/(n-k) * [s12*(n1 -1) + ... + sk2 *(nk -1)]
In this equation,
k refers to the k groups in the plot,
s12, refers to the variance in the i'th category or group,
n1 refers to number of valid observations in the i'th category or group, and
n is the overall number of valid observations in the plot.
The standard error of the mean for the i'th group is then computed as:
s.e.(mean) = spooled / square root(ni)
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| Multiple box layout
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The options in this group box are used to control the display of the Means with Error Plots in the graph. Note that these options are applicable only when you have selected more than one dependent variable, and if you selected Multiple as the
Graph type (see above).
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| Shifted
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Select this option button to display a series of Means with Error Plots for the selected dependent variables in different colors, side by side.
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| Overlaid
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Select this option button to display a series of Means with Error Plots for the selected dependent variables in different colors, one on top of the other.
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| Trim distribution extremes
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Specify the percent of cases to be trimmed from the extremes (i.e., tails) of the distributions of cases for the selected dependent variables. For example, if you specify
10%, for a variable with 100 cases, Statistica removes the 10 cases with the lowest values and the 10 cases with the highest values for the respective variable from the graph, and uses only the 80 remaining (middle) cases. If you enter a value for
Trim distribution extremes for mean-based Means with Error Plots, the so-called trimmed means will be used in the graph.
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| Whisker
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Specify the options for computing the range of
Whiskers or
High-Low Close, i.e., to define the error ranges.
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| Value
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Specify how the range of
Whiskers or
High-Low Close is computed. If you select Conf. Interval, the range will be displayed as the confidence interval around the mean value. If 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. The option
Min-Max uses the minimum and maximum values of the data to determine the range without considering whether these values are outliers. If you choose
Constant, the specified constant will be added/subtracted from the chosen center point (mean or median) to define the range around that center point.
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| Probability/Coefficient
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If you specify
Value (see above) as the 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. When the
Value option is set to
Constant, the value of the
Coefficient itself determines the range (no multiplier is used).
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| Outliers
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The options in this group box are used to control the display of outliers and extremes. Select either
Off,
Outliers,
Extreme, or
Outl. & Extremes from the drop-down box. See Outliers and Extremes for additional details on these options.
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| Coefficient
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If you select
Outliers,
Extreme, or
Outl. & Extremes in the drop-down box, specify a coefficient to be used to determine the outlier or extreme value range; see Outliers and Extremes for additional details.
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| Statistics
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You can choose to include a variety of statistics as a footnote in the graph by selecting one or more of the statistics listed in the
Statistics group box.
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| Kruskal-Wallis test
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Select this check box to include the Kruskal-Wallis test statistic as a footnote on the graph.
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| F test, p
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Select this check box to include the F test and p statistics (analysis of variance results) as a footnote on the graph.
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| Connect middle points
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Select this check box to connect the selected middle points (Means,
Medians, trimmed
Means, or trimmed
Medians) of the
Whiskers or
High-Low Close.
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| Display raw data
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Select this check box to display the raw data points.
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| Jitter
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Use the options in this group box to jitter the data points, i.e., modify the original position of the data point from the center of the graph in order to more easily identify/brush overlapping points.
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| Off
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No jitter is applied to the raw data points, outliers, and extremes.
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| Sequential
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The jitter is applied sequentially to the raw data points, outliers, and extremes. The jitter is applied such that the first case in the data set is maximally shifted to the left and the last case is shifted maximally to the right.
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| Random
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The data point is randomly shifted within the available range.
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| Width
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With this option, you can specify the maximum jitter width defined as percentage of box width. Possible percentages range from 0 to 250.
Options / C / W. See Common Options.
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| OK
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Click this button to accept all the specifications made in the dialog box and to close it. The results are placed in the
Reporting Documents workspace node after running (updating) the project.
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