All newspapers commit sins of commission, but I also fret about sins of omission. People or groups not identified fully. Important information left out. Someone who wasn't called.

I think readers want as much context as they can get when they read a Post story. It doesn't help readers when an organization, a business or an individual is not fully identified or if a person or group is criticized without their counter-balancing comment or an indication that it was sought.

Sometimes it's just a number. For instance, a Nov. 23 story on Iraq said the Pentagon "tentatively plans to reduce the number of U.S. forces early next year by as many as three combat brigades." Several readers pointed out that nowhere did the story say how many soldiers are in a brigade.

Scott Vance, the national security editor, said that providing a new bottom-line troop total was complicated by not knowing the number of associated support troops that would be cut along with the combat brigades, each of which has about 3,500 soldiers. He said the article should have explained that more clearly.

Several Post stories were written about Rep. John P. Murtha (D-Pa.) and the resolution he offered in the House on withdrawing U.S. troops from Iraq. Most of the stories used the word "immediate." I received a number of calls and e-mails -- perhaps politically motivated -- saying his statement did not call for immediate withdrawal.

An editor and I checked Murtha's Web site. While Murtha did use the word "immediately'' in his news release, both his House resolution and his news release had qualifiers. This was Murtha's language in the resolution: "The deployment of United States forces in Iraq, by direction of Congress, is hereby terminated and the forces involved are to be redeployed at the earliest practicable date."

The news release said his plan calls for the Bush administration "to immediately redeploy U.S. troops consistent with the safety of U.S. forces."

While "immediately" wasn't wrong, it wasn't quite right, either. It would have been better to say "at the earliest practicable date" somewhere in the stories or to add the qualifiers.

Defining groups as "activist" doesn't always cut it, either. What is an environmental activist? It could have a host of different meanings.

Reader Blaine Charak of the District asked what The Post's guidelines are on using the word "activist." He said he has seen the word used in Post stories without elaboration on what it meant.

Here's what The Post's stylebook says: "Be careful about the labels attached to people. References to civic leaders, AIDS activists, political activists, etc. are used much too freely. These are not designations for which there are settled criteria and using them too easily can render them meaningless. Activist is particularly bothersome. Who defines the category?"

Another omission I find troublesome is a reference to an organization without identifying information. Washington has dozens of think tanks with as many agendas. Most are "nonpartisan" to obtain their tax status as nonprofit groups.

I asked The Post's News Research Center to check on just three -- the Heritage Foundation, which leans conservative, the Brookings Institution, which leans more liberal, and the Cato Institute, which has a libertarian bent.

In the vast majority of stories this year, the three are not identified by their leanings. Cato has been mentioned in stories or op-ed columns 30 times, 16 times as libertarian. Heritage was mentioned 115 times, 45 as conservative. Brookings was cited 270 times, five as liberal-leaning.

A Post staffer might well say that these organizations are well known in Washington. Among the political cognoscenti, that might be true. But I don't think that most readers of The Post -- print or online -- would necessarily know that. I think that for clarity's sake these organizations' political orientation should be mentioned. There are a few exceptions when a scholar or analyst doesn't fit the organization's mold; that should be reported as well. Ron Haskins, a Republican at Brookings, would be one case.

We did not identify the National Priorities Project in a Nov. 4 front-page story about military recruiting, other than to describe it as a "nonpartisan research group." When I checked its Web site, it was clear that the group questions the war in Iraq. I called its public relations person and asked if the group is "liberal, left-leaning." "Sure," she said.

Anne Hull, a reporter I admire, did a fine two-part series Nov. 13-14 on the gentrification development around 14th and T Streets in the District; it gave a flavor from the ground up about what is happening to the area.

It had one omission. The story mentioned a flier describing in derogatory terms D.C. Council member Jim Graham, a Democrat who represents Ward 1, which is near the development. Hull did not call him for comment; she said she and her editor felt it was not necessary because she did not dwell on the flier. Graham felt wronged by not getting a chance to comment. I thought he was, too. That extra call would have made the piece well-nigh perfect.

Deborah Howell can be reached by phone at 202-334-7582 or by e-mail at ombudsman@washpost.com.