Measured from the side camera: the angle from horizontal through your shoulder to your ear. Higher is more upright, all the way down. A negative value means your ear has dropped below your shoulder, which is the head hanging forward onto the chest. Read the trend, not the absolute number: this is a raw angle from an uncalibrated camera, not the clinical craniovertebral angle, so no published threshold applies to it and moving the side camera shifts it more than weeks of real change do. Days with no line are days with no side-derived reading. That covers a side camera that was not connected, and equally a connected one that produced no readable angle, for example when an ear or a shoulder was not clearly visible, or when it saw you but the angle could not be measured. The gap says this measurement is missing for that day; it does not say why.
Counted over randomly sampled checks only, so the comparison is not biased toward frames the local measurement already flagged.
| When | Local | Gemini | Issue | Tip |
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