When a news story claims certainty in expressing public opinion — or uses sources that claim such — readers should be wary.

Such is the case with a Friday NPR story that commingled analysis, reporting, and commentary (without a commentary label) about the impact of “tough economic news” on President Obama’s re-election prospects.

Some phrasing in the 1,081-word story represents guessing or labeling instead of reporting: seems, perhaps, hardly has a pulse, appears, near certainty, dismal harbinger, liberal wing, political environment, seems a distant memory, progressive community, recent experiences, some in his own party (tell us who, please), and a pervasive view.

But it is proclamations of knowledge of public opinion that irritate most.

The story quotes William Galston as a domestic policy expert who worked in the Clinton administration:

Public opinion has coalesced around the proposition that meaningful deficit reduction is needed. The credibility of a Democratic-Keynesian response to joblessness is much diminished in the eyes of the public. [emphasis added]

It’s not apparent that after hearing this the NPR reporter asked Galston: “Where’s your evidence that public opinion has coalesced?” Similarly, support for Galston’s “much diminished” claim is inadequate at best.

The reporter, three grafs later, provides this: In 2009, polls showed that about 60 percent of Americans favored the stimulus effort: that dropped to 42 percent the following year. How does this support Galston’s claim about meaningful deficit reduction? (And polls do not show that “60 percent of Americans” believe such; they only show that 60 percent of poll respondents believe …)

Galston is allowed to make two claims about public opinion without explaining the basis for either. But hey, say readers: He’s an expert. He once worked in the White House. Therefore, he must be credible. But readers should not assume that; they should expect a story to adequately demonstrate credibility.

(It would have been helpful, too, if the story had explained the phrase “a Democratic-Keynesian response to joblessness.” Or does NPR expect all its readers to have a working knowledge of Keynesian economics?)

Later in the story, this:

Poll after poll shows that Americans now believe that cutting federal spending is the preferred path to job creation and expanding the economy, not government investment.

I spent an hour looking for such polls. I found one that applied to this generality — a New York Times poll published May 2. (See question 34.)

I found many polls that deal with which candidate or party has the ability to deal with the nation’s economy or the deficit here, here, and here. Reading the polls shows that respondents favor some aspects of budget cuts over others. For example, some polls show respondents favor cutting defense but not the social safety net or vice versa. Few deal with the singular question of “cutting the budget” wholesale that the NPR story claims “poll after poll” demonstrates.

This story is online. All the NPR reporter — or tech geeks or an editor — needed to do is provide links to the polls that the story says support points made. Claims about public opinion based on polling should not be made lightly, nor should readers accept them uncritically. Journalists should give readers more ability and authority to assess claims.

Use more detail; reveal more truth. Too many stories in too many media fail to adhere to this simple truth. This NPR story is just one example.

And this: If NPR had slapped a commentary label on this piece, you wouldn’t be reading this post.