Why do heart rate data from different devices not always match?

The article discusses the discrepancies in heart rate measurements reported by various wearable devices, such as smartwatches and fitness trackers. Key reasons for these differences include varying algorithms, sensor types, and parameters used in the devices. Physiological dynamics and different data analysis methods impact how accurately these devices assess users' health metrics. The study also considers human factors—such as body position, type of physical activity, and user error—that can lead to smaller or larger deviations in measurements. The article emphasizes the importance of selecting the right devices based on individual needs and expectations for obtaining the most accurate data regarding one's health status.