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Use Polygon's averaging feature to compare data in multiple trials or within the same trial. By default, the Avg + 1StDev and Avg -1 StDev trace is displayed in the Graph pane as a thick gray line.

The data are averaged using the first nominated normalizing range in or the average of all the nominated ranges for the contexts of each of the data files that are selected for averaging. If there is no context associated with a file, the data series are assumed to be pre-normalized and the whole series is used in the averaging.

Polygon averages only the data that can be found in all the input files. For example, if you have selected four different data files for averaging and only three of these contain angles, the result will not contain any angles. It is recommended that you check the data files for consistency before averaging.

When an average has been created, an average node is added to the Data Bar.

For further details, see:

Create an average for all trials

If analog EMG data is averaged, the enveloped EMG is averaged, not the raw data.
EMG data may not be associated with the correct context if the names of the data objects (as seen in the Data Bar) don't start with the correct letters (L and R in the case of Left and Right contexts). In this case, the data objects are associated with the default context and you may have to manually assign the different contexts to the different data objects prior to averaging.
  1. Click the Data ribbon and then click the All Trial Average button.
    The Average Data dialog box opens.
    The left list box shows the files that are available for averaging, and the right list box shows the files that have been selected in the current average node.
  2. Do one of the following:
    • To select an existing Average node, click the arrow in the Select Average Node box.
    • To create a new Average node, click Create and enter the name you want to use in the Enter Average Node Name box.
  3. Under Available for Averaging, select the trial(s) you want to average and click the right arrow button. To remove trials from the right box, click the left arrow button.
  4. Select the required options:
    • Under Preferences, select whether or not to include the following types of data series: angles, moments, powers, forces, scalars, analog data, and temporal data.
    • To average right and left data together, select the Average Data Across Contexts box.
    • To base the averages on the nominated cycles, select Use Average of Nominated Cycles.
      If you select this option, the result is based on more cycles (unless only one gait cycle is nominated in each trial). In other words, the same type of variable associated with different contexts will be combined. For example, two data objects named LHipAngle and RHipAngle are combined to HipAngle in the Average node. If averaging across contexts is not selected, the two variables are kept separate.
    • To select a number of sample points to use when performing resampling, enter a number in the box next to Number of Sample Points.
      For example, if you choose 51 (the default), each gait cycle is resampled using intervals of 2%. In general, these data points do not coincide with the sample points from the data files, so Polygon will linearly interpolate between the sample points of the data files to obtain the points to use for the averaged file.
  5. Click OK.
    A new Average node with a blue folder icon is created in the upper panel of the Data tab.

Add a trial to averaged data

  1. In the upper panel of the Data Bar, right-click the trial you want to add to the averaged data.
  2. Select Add <TrialName> Variables to Graphs.
    The trial data is added to the averaged data in the Graph pane and under the Average node in the lower pane.

Remove a trial from averaged data

  1. Click the Data ribbon and then click the All Trial Average button.
    The Average Data dialog box is displayed.
  2. In the Currently Selected In Average list box, select the trial to remove and click the left arrow button.
  3. Click OK.

Add a data type to averaged data

  1. In the upper panel of the Data Bar, open the node with the data you want to add (e.g., Kinematic Data).
  2. Right-click the data type and select Components.
  3. Select one of the following:
    • 1, 2, 3: Shows a single axis. You can change how this option is displayed in the Variable Ranges dialog box (found on the Graph ribbon)
    • All: Shows all components.
    • Separate: Shows each axis on a separate tab.

Average within a trial

  1. In the upper panel of the Data Bar, right-click the trial you want to average.
  2. Select Average Within Trial.
  3. In the Average Within Trial dialog box, select the options you want and click OK.
    A new Average node is created within the trial node with a blue folder.

Practice data averaging

Part 1

  1. Import several files into your report. Use the Data tab to select averaging options and create an average node.
  2. Create several graphs with hyperlinks to the average node data.
  3. Modify the graph display to show standard deviation and trace together.
  4. Import several trials and create several average nodes.
  5. Save the report.

Part 2

  1. Highlight each average node and save each average node as a separate .pxd file.
  2. Close the report and create a new report. Import .pxd files.
  3. Use the imported .pxd data to create an Average node.
  4. Save your new Average node as a .pxd file.
  5. Save the report.