- A stock is a better buy when it is at the low end of its risk range.
- A stock is a better buy when its Implied Volatility is at a premium (ie: when fluctuations are smaller due to a bull market).
The first one is a no-brainer. But both of these rely on the models and data that are used to construct these measurements. Also, the future price volatility cannot be predicted, just implied. Likewise, risk is ultimately subjective.