  The only acceptable form of polling in the multi-billion dollar survey
research field utilizes representative samples. We argue that with proper
statistical adjustment, non-representative polling can provide accurate
predictions, and often in a much more timely and cost-effective fashion. We
demonstrate this by applying multilevel regression and post-stratification
(MRP) to a 2012 election survey on the Xbox gaming platform. Not only do the
transformed top-line projections from this data closely trend standard
indicators, but we use the unique nature of the data's size and panel to answer
a meaningful political puzzle. We find that reported swings in public opinion
polls are generally not due to actual shifts in vote intention, but rather are
the result of temporary periods of relatively low response rates among
supporters of the reportedly slumping candidate. This work shows great promise
for using non-representative polling to measure public opinion and the first
product of this new polling technique raises the possibility that decades of
large, reported swings in public opinion-including the perennial "convention
bounce"-are mostly artifacts of sampling bias.
