Solution: Sharpe Ratio and Risk-Adjusted Return: mechanical calculation
Part 1
The relevant definition is the lesson's central relation:
This formula is meaningful only after the measurement convention is fixed.
Part 2
A minimal calculation uses clean inputs, applies the definition, and checks scale. If the result is a rate, compare it with nearby maturities. If it is a risk or performance measure, compare it with an economically similar asset or strategy. If it is an algorithmic estimate, compare it with a simpler baseline.
Part 3
The most important assumption is usually the convention that turns raw observations into the model input: annualisation, compounding, sampling frequency, objective function, or calibration measure. Changing that convention can change the result without any change in market economics.
Takeaways
- The definition gives the number, but the convention gives the number meaning.
- Sanity checks are part of the calculation, not a separate clean-up step.
- The finance use case here is manager selection, strategy comparison, and portfolio construction.