According to the game screens, building and upgrading an economic starbase (not an economic resource mining starbase) is supposed to help improve military, social and research production. For example, one of my starbases currently states on the starbase screen: Military, Social and Research Production: +25.

However, while upgrading this starbase with additional constructors to get up to the +25 bonus, I kept track of the military, social and research production numbers for the planets within the starbases radius. With each upgrade, it was noticed that the military and social production numbers would be increased by the expected percentages. However, research production did not receive any bonus whatsoever. This has been confirmed across several games, with several economic starbases.

Either the in game description is wrong (and should read that economic starbases only improve military and social production), or the game is not properly applying the research production bonus as it should.