According to TSP.gov my Personal Investment Performance (PIP) for the past 12 months ending 1/31/2017 is 17.12%.
The "help" link on the TSP site says:
The rate of return earned by your entire account during the 12-month period ending on the date indicated on your annual statement or on your Account Balance page of the TSP website. The PIP is a time-weighted return that has been calculated using the Modified Dietz method (a method used by many financial institutions and an industry standard). The PIP adjusts for the distorting effects of cash flows into or out of your account. It is an estimate; therefore, your PIP may not be the same as the 12-month performance of the TSP funds, which are time-weighted returns.
...but I am still in the dark. What does a PIP of 17.12% mean? Is that good? How is it calculated?