Yes, you can use the IF function within the STDEV function to calculate the downside deviation.

1. First, calculate the minimum acceptable return (MAR) and the expected (observed) return for your investment portfolio.
2. Next, create a range of returns for your investment portfolio. Let's say the range is
   Formula:

   A1:A10 

   .
3. Use the IF function to create a new range that only includes returns that are less than the MAR. The formula would be:
   Formula:

   =IF(A1<MAR,A1,"") 

4. Copy the formula down the range to include all the returns in your portfolio.
5. Now, use the STDEV function to calculate the standard deviation of the new range you just created. The formula would be:
   Formula:

   =STDEV(range) 

6. Finally, use the Sortino Ratio formula to calculate the ratio. The formula would be:
   Formula:

   =(Expected Return - MAR)/STDEV(range) 


By using the IF function within the STDEV function, you can calculate the downside deviation (standard deviation of returns less than MAR) and use it to calculate the Sortino Ratio.