People kept bringing up the Sharpe Ratio, and it made me wonder if the SOA would accept it, because you can kinda-sorta derive it using the metrics given.
Sharpe Ratio = (alpha - r) / sigma
We are not given alpha, nor r, nor sigma.
However, we are given certain parameters:
-Mean cost of selected portfolio
-Mean cost of T-Note-based portfolio
-Standard deviation of cost
alpha is negatively correlated to mean cost of selected portfolio (in other words, alpha ~ -1 * cost_of_selected)
r is negatively correlated to the mean cost of the 100% t-note portfolio (r ~ -1 * cost_of_tnoteportfolio)
sigma is positively correlated to the standard deviation of the cost of the portfolio (sigma ~ -1 * stand_dev)
sub in the new parameters and you get the formula that Sir Isaac mentioned in the thread linked to above,
The Sharpe Ratio can more-or-less be represented using (Cost of T-Note portfolio - Cost of Selected Portfolio)/(Stand Dev. of Selected Portfolio).
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If you feel uncomfortable doing this, I think the point is for you to use at least two metrics, one of them measuring risk and the other measuring return.
The whole point of step 1 in task 2 was for us to understand that NO SINGLE MEASURE WILL BE ADEQUATE.
Find one that measures risk, find another one that measures return, and figure out how the minimum/maximum of their product/divisor to determine the "best" portfolio. At this point, I'm 95% certain that's what the SOA wants us to do.