Fig. 1: Example of raw, primary, and secondary features inside the Cortex platform, which is a software pipeline that transforms digital phenotyping raw data into meaningful features.
From: Digital health technologies in the accelerating medicines Partnership® Schizophrenia Program

In this figure, raw data (on the far right) is GPS and primary features are trips and secondary locations. Secondary features are derived from primary features and, in this example include home time, trip distance, and similarity measures of mobility patterns across different weeks.