An actuarial valuation is a type of appraisal which requires making economic and demographic assumptions in order to estimate future liabilities. The assumptions are typically based on a mix of statistical studies and experienced judgment. Since assumptions are often derived from long-term data, unusual short-term conditions or unanticipated trends can occasionally cause problems.
A common example where an actuarial valuation is in the valuation of a pension fund. It is usually easy to value a pension fund's assets because they primarily hold liquid securities such as stocks and bonds. However, it can be very difficult to value the liabilities of a pension fund. First, assumptions must be made to determine the total value of pension payouts that must be made in the future. Second, assumptions must also be made as to the expected growth of the fund's assets which will allow it to meet those obligations. If either set of assumptions proves to be significantly off, then there might be too little (or too much) funds in the future to pay pension benefits.