Test it in a field experiment! 

Alan S. Gerber and Donald P. Green. 2012. Field Experiments: Design, Analysis, and Interpretation. W. W. Norton & Company. 

Alan S. Gerber, Donald P. Green, and Christopher W. Larimer. 2008. “Social Pressure and Voter Turnout: Evidence from a Large-Scale Field Experiment“, American Political Science Review 102(1), 33-48.