The choice of index fund is related to the fund manager, and the investment target of index fund is selected by the fund manager. If the investment level of fund managers determines the tracking error of index funds, it also determines whether index funds can obtain excess returns.

The tracking error mainly depends on the deviation between the fund and the tracking target. Generally, the smaller the tracking error, the better. The smaller the average tracking error is, the closer the trend between the fund and the tracking target is. Tracking error is an important index for selecting index funds.