CareDx(CDNA) - 2023 Q4 - Annual Report

Stock-based Compensation We use the Black-Scholes Model, which requires the use of estimates such as stock price volatility and expected option lives, to value employee stock options. We estimate the expected option lives using historical data, estimate volatility using our own historical stock prices, estimate risk-free rates using the implied yield currently available in the U.S. Treasury zero-coupon issues with a remaining term equal to the expected option lives, and estimate dividend yield using our exp ...