CDE Detailed Report

Head impact exposures observed on video but lacking corresponding device exposure data within the allowable time-period (Maximum Allowable DeltaT). Through careful review of the video, identify head impact exposures. The definition of this will vary by the sport setting studied but could include identifiable change in the head kinematics (in the case of a head impact in football for example) or an identifiable change in the ball trajectory (in the case of a head to soccer ball impact). It is highly suggested that this process be conducting by multiple coders blinded to each other's' efforts. Have a master coder reconcile any differences in exposure identification. Count the number of head impact exposures identified on video that do not have any corresponding data on the device within the allowable time-period.

The number of visually verified head impact events that resulted from head to head contact (including helmet to helmet contact).

The number of visually verified head impact events that resulted from head to body contact (e.g., head contacts the torso of another person).

The number of visually verified head impact events that resulted from head to ground contact (e.g., while falling or diving, head contacts playing surface).

Please indicate method of creating timestamps on video footage. The approach used to generate a timestamp for each individual video frame used to verify impacts. The timestamp is the time of day of a given video frame which will be compared with the time of day an event is recorded via the device. The timestamp can be generated by the camera using an internal clock (e.g., a GPS synched clock, an internal software clock, etc.) or can be tracked using an external source (e.g., a digital clock in view of the camera, calibrating the frames using a digital clock shown a single time, etc.). These methods are not exclusive, and other approaches may be described.

When date/time data are prepared for aggregation or sharing they should be converted to the format specified by ISO 8601, YYYY-MM-DDThh:mm:ss.

The number of visually verified events in which the person's body comes in contact with another person, the ground, or an object that result in an "acceleration event" of the head – without direct contact to the head.

Data is best described when video and data correspond (option 3). The accelerometry device and video recording can independently capture exposure information and can be cross-verified to increase confidence of the exposure measurement. This CDE differentiates which set of information serves as the ground truth for verification. For example, if video is served as ground truth, exposures captured on video but not measured by the device would be considered as missing (false negatives). It is also an option to only consider exposures measured by both the video and the device to be 'verified' exposures. Please select from following options or, if another method is used, provide a detailed description of the method.

Please indicate all activities under study which pertain to the subject (e.g. football, soccer). Associated CDEs are C56787, C56855, and C56826.

When date/time data are prepared for aggregation or sharing they should be converted to the format specified by ISO 8601, YYYY-MM-DDThh:mm:ss.

Where DeltaT is the amount of time between an identified device/video exposure(s). Due to uncertainties in real-time stamps or time offset calculations, the timing of individual exposures may not have an exact match between video and device. For example, if there is a +/- one second uncertainty in the timestamp, it is possible that a video exposure at 12:30:45 may be matched with a device exposure at 12:30:46. This CDE specifies the amount of tolerance allowed for the difference between video and device time stamps. Indicate time offset in number of seconds between video and device time stamps allowed for linking exposures.

These could include those events where there is device data but video data is not available (e.g. player out of frame, etc).