son 1 contributed much less data (n = 722) than person 2 (n = 14031). This can be explained by the different devices that were used by both: Person 1 used an iPhone (with standard GPS-settings) and Person 2 used a Sony Z1 Android (with high-precision GPS features enabled). This device-related variability in GPS sample rates and accuracy is one of the primary challenges of naturalistic EMA research and EMI applications.</p>
<p>The problem with the (in)accuracy of GPS-data is further illustrated by Figure <a 