| Contribution
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The
Contribution group box contains options for calculating variable contributions to the scores.
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 Contribution
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Click this button to generate a histogram of variable contributions.
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 . (Contributions Spreadsheet)
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Click this button to generate the histogram of variable contributions in spreadsheet format.
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| Obs
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Specify the observation for which you want to generate a histogram or spreadsheet of variables contributions (see above).
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| Lineplot (p)
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Click this button to create a line plot of the loading factors for the principal component selected in the
First component list (see below). To generate more than one graph, make multiple selections. Note that different variables contribute differently to the loading factor of a principal component. The loading factors determine the orientation of the principal components with respect to the original coordinate system. The more influential a variable, the larger its loading factor. Thus, by examining the loading factors, we can tell how different variables contribute to the principal components.
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| Scatter (p)
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Click this button to generate a scatter plot of the loading factors for the principal components selected in the
First and
Second lists (see below). The loading factors determine the orientation of the principal components with respect to the original coordinate system. To generate more than one graph, make multiple selections in the
First and
Second lists. For instance, you can generate the scatterplots of components 1 and 2 vs. 3 if you select components 1 and 2 in the
First list and 3 in the
Second. Observations falling outside the limit defined by the ellipse will be marked in red. These may be signs of abnormality, which you may want to further investigate.
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| Lineplot (t)
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Click this button to create a score line plot for the principal component selected in the First component list (see below). To generate more than one graph, make multiple selections from the list.
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Click this button to display the data generated in the
Lineplot (t) option (described above) in spreadsheet format.
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| Scatter (t)
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Click this button to create a scores scatterplot for the principal components selected in the
First and
Second components lists. The t-scores are the representation of the original X variables in the principal component system. To generate more than one graph, make multiple selections in the
First and
Second lists. For instance, you can generate the scatter plots of
Components 1 and 2 vs. 3 if you select
Components 1 and 2 in the
First list and 3 in the
Second. Observations falling outside the limit defined by the ellipse, defined as:
will be marked in red. These may be signs of abnormality, which you may want to further investigate.
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Click this button to display the data generated in the
Scatter (t) option (described above) in spreadsheet format.
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| Biplot
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Select the Biplot check box to augment the component scores scatterplot with variable projections. The specific variables projected into the component space can be selected by clicking the Variables button.
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| Standardized plot
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Select the Standardized plot check box to standardize the biplot, that is, display the standardized component scores and standardized variable projections.
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| Variables
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Click the Variables button to display the
Biplot variables dialog box. The variables selected are displayed as variable projections in the biplot.
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| First
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This list displays the principal components for the
PCA model. The principal components selected from this list will be used to form the x-axis for plotting the scores and loading factors (see above).
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| Second
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This list displays the principal components for the
PCA model, and is used only for scatterplots. The principal components selected from this list will be used to form the y-axis for plotting the scores and loading factors (see above).
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| Plot labels
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The following three options are contained in the
Plot labels group box:
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| No name/number
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Select this option button to exclude variable names or case numbers (whichever is appropriate) from the graphs of scores and loading factors (line plots and scatterplots).
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| Var/case number
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Select this option button to include variable or case numbers (whichever is appropriate) in the graphs of scores and loading factors (line plots and scatter plots).
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| Var/case name
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Select this option button to include variable or case names (whichever is appropriate) in the graphs of scores and loading factors (line plots and scatter plots).
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| Limits (t)
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Use the options in this group box to define limits for the score plots (line or scatter).
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| Multiple of std. dev.
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Select this option button to define the upper and lower bounds for the score limits as control standard deviation.
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| Compute from p
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If you select this option button, Statistica will assume that the scores are normally distributed and the 99% confidence levels are used to define the upper and lower limits.
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| Control
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Specify the control limits. When the Multiple of std. dev. option button is selected (see above), this value is multiplied by the computed standard deviation for defining the upper and lower limits.
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| Warning
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Select this check box to include an upper and a lower warning limit in the scores graph. In the adjacent box, specify the warning limit. For the Multiply std. dev. option, this value will be multiplied by the standard deviation for the scores to define the lower and upper warning limits.
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