Analysis of the quality of electrodermal activity and heart rate data recorded in daily life over a period of one week with an E4 wristband
Wearable technology allows the monitoring of several psychophysiological responses, like electrodermal activity (EDA) and heart rate (HR) in real time and in daily life over a period of days and weeks. This paper serves as an introduction to a new approach which tries to warn alcoholics based on their psychophysiological responses, in order to prevent relapse. However, the first step is to determine the quality of the recorded data which is discussed in the present paper regarding the amount of data which is artifact free and can be used for further analysis. An experiment was conducted with eight participants with a heavy drinking behavior over the period of one week. They wore the E4 wristband from Empatica which is capable of measuring EDA, HR, inter beat interval (IBI) and blood volume pulse (BVP) among others. Several analyses were applied including standard analyses via Matlab, as well as self programmed analysis programs. The results state a high quality of the EDA data, with around 90% of the data detected as clean signal and is thus suitable for a further analysis including drawing reliable conclusions from it. Regarding the HR, only 2% of the data was determined as possible artifacts, in contrast to the IBI data where only 15% of the possible maximum values could be measured. This great difference can be explained by the BVP measurements which are used to compute the HR and the IBI, whereby the HR is always computed or estimated and the IBI only on the basis of sufficient measurements. However, it is still possible to use the HR data, but it is important only to use fractions of the data and never base a decision solely on the HR or IBI data.