Differences

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--- other:inspect3d:tutorials:perform_principal_component_analysis [2025/01/17 15:24] – wikisysop
+++ other:inspect3d:tutorials:perform_principal_component_analysis [2025/01/17 15:24] (current) – wikisysop
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 === Workspace Scores ===
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+{{:inspect3d_oa-NC_Workspace_Scores.png}}
 Having identified our principal components of interest, switch to the Workspace Scores window and plot the chosen principal components against one another (i.e., for this tutorial, plot PC1 versus PC2). We are looking to be able to distinguish our groups and in this case there is a pretty clear separation between the groups in this 2D space. Although PC1 may describe more of the data set's variability than PC2, PC2 can discriminate between the groups better (this isn't mathematically shown here, but can be seen if the visual inspection is followed by a cluster analysis). Of course, PC1 and PC2 can discriminate between the groups even better if they are used together instead of separately.
 If you want to investigate the original data for a particular workspace, click on the workspace's scatter point and the corresponding data will be highlighted in the original Queried Data plot. Similarly, if you click on a trace in the original Queried Data plot then the corresponding workspace is highlighted in the Workspace Score widget. This can be useful to identify outliers.
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 For the **Plot Type** drop-down menu, select the Mean and Slider option. Leave the **PC Number** set to 1 and then click **Play**. The mean reconstruction (gray in the figure below) will remain static while the other reconstruction (blue in the figure below) will vary in the range Mean +/- 2 Standard Deviations. Watching this animation demonstrates that PC1 is capturing variability as an offset in the signal. Vertical offsets in gait data can occur for a variety of reasons, including differences in standing calibration posture. Therefore, PC1 may explain a significant amount of variability that is not very helpful for answering our question.
-{{ :inspect3d_oa-NC_Extreme_Plot.png?600 }}
+{{:inspect3d_oa-NC_Extreme_Plot.png}}
 Now select **PC Number** 2 and click **Play** again. This PC shows a different story, with the largest differences in this animation occurring during late stance and mid-swing.