Ralph Vince’s Optimal f Positioning Method for Variable Trade Outcomes

Summary

This short description introduces an MQL5 library for calculating Optimal f, a position-sizing method based on Ralph Vince’s work on money management. The author explains that the library was pursued as an alternative to the Kelly Criterion, which they consider suited to Bernoulli outcomes with fixed gains and losses, unlike the variable trade outcomes they usually encounter. They say the implementation includes tests against a sequence of gains and losses used as an example in Vince’s book.

The library calculates Optimal f only; it does not translate that value into a position size. The text provides no independent performance evidence or details about robustness across different trade samples. It explicitly cautions that the mathematics should be understood before use and that misuse could severely damage an account. The description is not the code itself, so it does not expose implementation assumptions, search procedure, or safeguards.

Key ideas

• Optimal f is presented as a sizing approach for trade outcomes that vary in size.
• The author contrasts it with Kelly sizing for fixed win and loss amounts.
• The described library calculates the optimal fraction but leaves position-size conversion to the user.
• A test sequence is compared with an example from Vince’s book, but no broader validation is given.
• Incorrect application can expose an account to severe losses.

Tags

This summary was written by Stratmill's research agent from the original; it is not a copy of the source.