In early July, the Pew Research Center found that 65 percent of respondents said the campaign was not focused on important policy debates. A study released by Harvard's Shorenstein Center on Media, Politics and Public Policy is now lending credence to that sentiment.

The researchers – having studied news statements from eight major outlets during the primary season between January 1 and June 7 – concluded that "substantive concerns" accounted for only 11 percent of the campaign coverage. Receiving far greater attention were the "competitive game" and "campaign process," accounting for 56 percent and 33 percent of the coverage, respectively.

The study found that this shortage of substantive coverage was consistent across both parties' contests.

"There was no appreciable variation between the Republican and Democratic coverage," the report states. "In each case, the competitive game was the primary focus and in nearly equal amounts, while substantive concerns got the least amount of attention, again in nearly equal amounts."

The report attributes the lack of substance to the contradictory values of politics and journalism. Democratic politics, on the one hand, requires an educated electorate that can grasp and debate complex policy issues. Journalism, on the other hand – especially election coverage -- tends to focus on the sensational and the superficial.

"Election news carries scenes of action, not assessments of the values reflected in those scenes," the report states. "Election news emphasizes what is controversial or different about events of the past day rather than what is stable and enduring."

The report also stresses the unique nature of the American primary process, borne of reforms enacted by both parties in the 1970s, that has created a months-long electoral procedure. The "plot-like nature of the competitive game," the report finds, causes journalists to cover the campaign as a prolonged "horse race."

"Whereas policy issues lack the day-to-day novelty that journalists seek, the game is always moving as candidates adjust to the dynamics of the race and their position in it," the report states. "The game is a perpetually reliable source of fresh material."

It is for these reasons, the authors claim, that substantive issues receive less attention than the "competitive game" during the modern primary season. And when candidates' policy positions are covered, they are often framed in terms of how their stances might affect their electoral performances, rather than what they might portend for the country. One Washington Post article from March, for instance, sported the results-oriented headline, "Trump’s Immigration Stand Expected to Help in Arizona, but Hurt in Utah."

The study found that candidates' performance in their respective races tended to affect the tone of their coverage, and thus, by extension, may have shaped voters' perceptions of the candidates. Candidates who performed well in primaries and caucuses, and candidates who exceeded expectations, tended to receive positive coverage, and candidates who performed poorly or below expectations tended to receive negative coverage.

During the competitive stage of the Republican primaries, for example, Trump received net positive coverage because he performed better than anticipated. Marco Rubio, on the other hand, consistently received negative coverage because of his failure to live up to expectations.

"For his part, Rubio never had a single week where his positive press outpaced his negative press," the report finds. "He had been pegged as 'the Republican establishment’s best chance' on the eve of the Iowa caucuses, but failed to come out on top there, or in any of the three states that followed. Rubio was a 'losing ground' candidate, and there’s very little that’s positive in that narrative."

The report finds a similar trend on the Democratic side: Sanders received net positive coverage in the first several months of the contest because he exceeded expectations, whereas Clinton received net negative coverage, in part because the race was closer than anticipated. The tone began to switch, however, as Clinton's lead in delegates became increasingly insurmountable toward the end of the primary season.

The report, as its subtitle declares, comes with a stark conclusion: "horse race reporting has consequences."

One consequence is that voters' attitudes of the candidates are shaped by media coverage, which is itself shaped by the candidates' performances. In other words, by giving positive coverage to winning candidates and negative coverage to losing candidates, the media can reinforce a candidate's positive momentum or contribute to a candidate's decline.

"The media’s tendency to allocate coverage based on winning and losing affects voters’ decisions," the report states. "The press’s attention to early winners, and its tendency to afford them more positive coverage than their competitors, is not designed to boost their chances, but that’s a predictable effect."

Another consequence of horse race reporting, according to the report, is that voters are deprived of valuable information about the candidates' policy stances – information they need in order to make informed choices.

"They are greeted by news coverage that’s long on the horse race and short on substance," the report states. This dearth of substantive information, in the words of political scientist Henry Brady, forces primary voters "to choose before they are ready to do so.”

In the end, the report is skeptical about the possibility of the media to reform the nature of its coverage, citing the values that determine its journalistic approach to reporting on the presidential race.

"The problems associated with press coverage of the 2016 nominating campaign are rooted in the mismatch of journalism values and the structure of the nominating process," the report claims. "There is little question that the nature of the 2016 campaign—Trump’s presence, particularly—brought the mismatch into sharp relief. But the broad tendencies in press coverage of the 2016 coverage are ones that exhibit themselves every four years."