Semi-variance is preferable to total variance as a measure of risk, given that risk should focus on "disappointing" returns that are below the expectation rather than "delightful" returns that are above expectation. An even better measure is risk relative to the investor's "minimum acceptable return" as defined by Frank Sortino. If we must think of the client's goal in terms of a return (rather than a monetary outcome) then the return that is expected to meet the client's financial goals should be used to define and to quantify any risk measure. This "lower partial moment" approach to risk takes a little more work, but it is much more intuitive and relevant than these other academic measures of risk.