The popular belief is that the candidate spending the most money on advertising has an advantage over all the other candidates (in a presidential race). But it hasn't worked out that way in the 2016 presidential campaign -- at least so far.
Note the chart at the top. It shows the amount of money spent by each presidential candidate in the 2016 primary season. Jeb Bush ($82 million) and Marco Rubio ($55 million) spent far more money on advertising than any of the other candidates. Where are they now? Both have dropped out of the race. All that spending did them very little (if any) good.
The public doesn't seem to be paying a whole lot of attention to the paid ads this year. But that doesn't mean they aren't paying attention at all. It seems that the free media (network and cable news and social media) has been far more effective this year. That's what the public is paying attention to.
Note the chart at the bottom. It shows the value of the free media each candidate has received this year. Note that the candidates receiving the most free media are the ones who have done the best -- Donald Trump and Hillary Clinton, and to a lesser extent Bernie Sanders and Ted Cruz.
Some may think that shows the unfairness of the media -- that they cover the candidates they like. I don't think so. The media covers stories (and candidates) that are interesting (because they are a profit-making venture). It is more likely that those candidates are the ones who have learned how to manipulate the free media the best. Trump is the master of media manipulation, but Clinton, Sanders, and Cruz are learning fast -- and they have all benefited from that.
The campaign game seems to have changed, and candidates can no longer depend on telling their story through paid ads. Today, a candidate must make themselves interesting enough to be covered by network and cable news, and learn how to use social media to their advantage.
The charts above were made from information in the New York Times.