The purchase of funds is based on the unit net value. General fund issuance is 1 yuan, and the total income (excluding some expenses) divided by the share of total investment plus 1 yuan is the unit net value. During the operation, dividends may be paid or split, and then the unit net value may be reduced. Another statistical method is cumulative net worth, which is not affected by dividends or splitting, and the income has been accumulated. The high cumulative net value indicates that its historical performance is good.