1. A device comprising: a sensor comprising a light emitter and a light detector configured to generate signal samples, wherein each signal sample includes a first signal generated when the light emitter is on and a second signal generated when the light emitter is off; and processing circuitry capable of: performing one or more variance calculations for each signal sample; predicting a condition of the device based on the one or more variance calculations for each signal sample; and determining that the device is not secured to an object when the predictions of the condition of the device for the signal samples meet a threshold.