There have been significant concerns in some political groups about foreign interference via social media on many recent elections. But there seems to be little hard evidence that any content on social media has any significant influence on the way people vote.
This recent story seems to provide a partial answer to that question (though it does not address the issue of whether foreign interference matters). The story addresses the (narrower) question of whether political advertising on Facebook has any influence. The Register reports it like this:
...researchers from the University of Warwick in England, ETH Zurich in Switzerland, and the University Carlos III in Spain, assert that Facebook ads do influence elections, but only among certain voters...
...The researchers contend that social media campaigns worked well to encourage undecided voters to support Donald Trump and to increase Republican voter turnout on election day significantly.
The original analysis is here.
Is the analysis credible? Did Facebook ads make a significant difference to voting patterns in 2016?
NB This is not a question about foreign interference but about the narrower issue of whether social media content of any kind has a significant effect.