Knowledge Base

Definition

A discrete (state event) variable with two possible states: Straight and Bent, depending on where the running average body angle (see Body angle for its definition) of the subject calculated for the current sample lays relative to a user-defined threshold:

• If the running average body angle is greater than the threshold value, the state is Bent. This state can be further split in Bent counterclockwise and Bent clockwise depending on the sign of the angle.
• If the running average body angle is smaller than the threshold value, the state is Straight.

The running average body angle is calculated for each sample, over the number of samples specified by the Averaging interval.

Below: Visualization of Body angle state (top chart) and Body angle (bottom). Body angle state was based on the Body angle values smoothed with averaging interval of 5.

How to Specify Body Angle State

1. Click the Add button next to Body angle state and click the Body Angle State tab.
2. Enter the following:
   • Averaging interval: The number of samples over which the running average body angle is based.
   • Body bent above: The angle above which the subject is considered to be bent. This value is unsigned and applied to both negative and positive Body angles.
3. Under Calculate statistics for, select which state you want to calculate statistics for: Straight, Bent, Bent counterclockwise (that is, when the running average body angle is positive; see Body angle for its definition), and Bent clockwise (when the running average body angle is negative).
4. Complete the procedure to add the variable. See Calculate statistics: procedure.

Notes

• When a body point is missing for more than three samples, the current Body angle state ends and the remaining missing samples are ignored.
• Averaging interval: The default value is 1. In that case the body angle state is based on the value of Body angle at the current sample. If you select a number k higher than 1, EthoVision takes the body angle of the last k samples (including the current sample) and replaces the current value with the average. See Averaging interval.

Source: EthoVision XT 19 Help, Noldus Information Technology