Now, a group of data scientists, journalists and Silicon Valley entrepreneurs is seeking to upend that reporting tradition, providing detailed projections of who is winning at any given time on Election Day in key swing states, and updating the information in real time from dawn to dusk. The plan is likely to cause a stir among those involved in reporting election results and in political circles, who worry about both accuracy and an adverse effect on how people vote. Previous early calls in presidential races have prompted congressional inquiries. The company spearheading the effort, VoteCastr, plans real-time projections of presidential...