If David Letterman introduces a "Stupid Journalists' Tricks" shtick to alternate with "Stupid Pet Tricks" on his late night television show, he won't lack material. From just the past few weeks, these howlers:

* Big headlines that homicide rates in the United States continued an historic decline. Reporters of this news gave no clue that they recognized a fundamental cause: Dramatic improvements in trauma care, including breakthroughs in medical technology. These  mean that more Americans now survive what previously would have been deadly attacks.

British prison psychiatrist-turned-writer, Theodore Dalrymple, has pointed out that after the United Kingdom abolished capital punishment in 1965, its homicide rate doubled. But better medicine has reduced fatalities from violence by up to four-fifths. So Britain's rate of what previously would have been homicidal mayhem has jumped as much as 10 times.

What about here in the States? Journalists didn't check. 

* More false comparisons appeared in uncritical reporting of the Centers for Disease Control and Prevention's National Intimate Partner and Sexual Violence Survey. It found that 1.3 million women had been raped and another 12.6 million women and men were victims of sexual violence in 2010.

It took an opinion column, not a news article, by Christina Hoff Sommers of the American Enterprise Institute, to point out that the CDC's figures were based on highly elastic definitions of sexual crimes. Sommers also calculated that CDC's numbers were 70 times higher than the number of such incidents reported in the FBI's National Crime Victimization Survey. Not twice as much, not seven times greater, but 70.

Even allowing for rapes unreported in the bureau's statistics, the National Intimate Partner and Sexual Violence Survey demanded much closer press scrutiny than it received.  

* Celebrating the drop in unemployment from 8.5 to just over 8.3 percent,  journalists did often note that if discouraged full-time job seekers who settled for part-time work or stopped searching altogether were added, the rate would be closer to 16 percent. But that still left a big hole in the news donut. Since the start of the Great Recession in 2008, an estimated six million jobs have disappeared, many permanently.

The overall workforce in the United States -- the figure upon which employment and unemployment rates are calculated -- has declined from 146 million to 140 million, while the population has risen from an estimated 305.5 million to 310.5 million. Today's unemployment rate (not counting part-timers or discouraged drop-outs) would be nearly 11 percent if the workforce was still as big as 2007's.     

* News reports frequently provided Americans with a misleading picture of the rise of Egypt's fundamentalists. Immediately after the overthrow of Egyptian President Hosni Mubarak a year ago, journalists found experts who estimated popular support for the "moderate Islamist" Muslim Brotherhood at no more than 25 percent. Completely off the news radar were the even more reactionary Salafists.

Yet last month the Muslim Brotherhood's Freedom and Justice Party won 47 percent of the seats in the lower, more important chamber of the Egyptian parliament. The Salafists' al Nour Party gained 25 percent.

It required another opinion column, not a news story, to point out that what the Brotherhood says on its Arabic Web site is far more radical than the items posted on its English site. Also, wrote David Pollock of the Washington Institute for Near East Policy, "many of the [Brotherhood] Freedom and Justice Party's actual moderates "have left or been expelled, and its most senior leaders are the hardliners .... [O]ne thing that has not changed is the Brotherhood's hostility toward U.S. policies and interests."

The First Amendment guarantees freedom of the press. But news consumers are on their own  against Stupid Journalists' Tricks.

The writer is a Washington, D.C.-based news media analyst. Any opinions expressed above are solely his own.