It doesn't matter, even a fully actualized public owned economy still requires that it estimate and compare production and capital increase so it knows 1. How much to alot for each citizen in the daily/weekly/monthly UBI, and 2. How to compare its production capacity and volume of capital to other countries who may or may not also be collectivist.

Both of these needs require the exact understanding of production increase so that it can accurately estimate the capital (capital in this sense being the amount of wealth set aside specifically for the increase in production capacity/efficiency) that allows the economy to grow. Thus they can take that information and increase the amount of dollars available to the country or it's citizens for use or trade with other nations.