Per definition, Sortino ratio calculates the Downside Standard Deviation by discarding all +ve returns (or returns > "risk-free rate") in the calculation of Std Dev.
I looked at the code of the Sortino ratio indicator function in http://www.quantshare.com/item-1146-sortino-ratio-of-an-asset
and it seems to be throwing away all returns > Average return (not 0 or risk-free rate). This would distort the interpretation of Sortino ratio.
See the code snippet below (trading object also attached) that states - if(ret[j] < avg) { dsdv = dsdv + Math.Pow(ret[j] - avg, 2); }
- Am I missing something?
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