Reviews:
This white paper evaluates the accuracy of the Stryd's measurement of running power, ground time, and vertical oscillation, by comparing it with a lab grade force plate-based treadmill and a metabolic measurement system: https://storage.googleapis.com/stryd_static_assets/stryd-metric-validation.pdf
Third-party review of Stryd's distance measurements (accuracy & precision): https://blog.stryd.com/2017/02/11/stryd-is-most-accurate-device-tested-by-fellrnr/
Secret of Running: VO2 & Stryd Power data https://thesecretofrunning.com/wp-content/uploads/2017/10/24.-How-to-use-your-Stryd-data-to-calculate-your-VO2.pdf
Detailed information on how to use Leg Spring Stiffness: https://www.trainingpeaks.com/blog/using-leg-spring-stiffness-to-measure-running-economy/