We maintain a daily count based on news reports. It is not intended to be complete. There is no agency that keeps track of accurate numbers of Iraqis killed. JustForeignPolicy maintains a running estimate based on the Lancet study with the rate of increase derived from the Iraq Body Count.

BAGHDAD - In the evenings, women in black gather at Umm Fatin's house to remember the dead.

Each family in the four neighboring houses in Tahrir, a former Sunni insurgent stronghold in Baqubah, has lost loved ones to bombings or shootings. Yet these deaths and countless others have fallen under the radar of the Iraq war. Nobody keeps an accurate tally of Iraqis killed because nobody knows.

As the Iraq conflict approaches its sixth anniversary, the number of American troop deaths - more than 4,250 - has been meticulously logged by the US military. Yet analysts are no closer to knowing how many Iraqi civilians have been killed, and they acknowledge a credible death toll will probably never be recorded.

Advocates say it is important to keep trying to provide closure and pave the way for reconciliation, as the Americans withdraw and the Iraqi public begins looking forward amid a decline in violence. They also say lessons learned could prevent similar tragedies.

"Unfortunately, there will likely never be an accurate statistic of civilian loss in Iraq. But what's important now is to get this right in Afghanistan and future conflicts and to get appropriate help to all Iraqis who've suffered in this war," said Sarah Holewinski, executive director of the Campaign for Innocent Victims in Conflict.

Estimates of the number of Iraqis killed since the war started on March 20, 2003, range from nearly 91,000 to more than 600,000.

One study, considered the largest and most scientific so far, concluded that about 151,000 Iraqis died from violence in the first three years of the war. But that survey by the World Health Organization and the Iraqi government included combatant deaths and covered only the period through June 2006. The uncertainty range was in the tens of thousands.

Efforts to count civilian deaths have faced obstacles ranging from brutal violence that prevents on-the-ground reporting to a lack of expertise after the devastation of Iraqi institutions and the loss of records in the chaotic aftermath of the US invasion.

The Health Ministry itself was long accused of being infiltrated by Shi'ite militiamen who were behind some of the worst sectarian violence. International aid agencies and human rights monitors do not have complete tolls either because they largely pulled out after a spate of attacks in 2003.

What is left is anecdotal evidence, and that is plentiful. It is hard to find an Iraqi whose life has not been touched by the violence that pushed the country to the brink of civil war.

Baqubah, where Umm Fatin lives, was one of the main flash points in the battle against Al Qaeda in Iraq and Shi'ite extremists. The 45-year-old housewife, who asked to be identified only by her nickname, lost her husband and son-in-law in a car bombing in 2007.

"My sorrow is not only because I lost my husband, but for my poor daughter, who was left a widow with two young children to care for when she is only 18 years old," she said.

Her neighbor, Mohammed Aziz, remembers the day in 2006 when gunmen opened fire on his car, killing his wife and 6-year-old daughter, Noor.

Another neighbor and his two brothers were killed by Shi'ite militiamen who broke into his small spare parts store. His mother can sometimes be seen by the door calling for her sons as if they were still alive.

The fourth house used to be owned by Abdullah Hadid. He was killed by Shi'ite militiamen who stormed his barbershop in 2006, leaving his wife and four children to fend for themselves.

There are clues to the death toll, such as the number of people buried at the main Shi'ite cemetery in the holy city of Najaf. But even here, the deaths were limited to mostly Shi'ites and included natural as well as violent causes, so they cannot be considered definitive.

The director of the cemetery's statistics office, Amar al-Ithari, said the number of people buried there jumped from just over 32,000 in 2004 and 2005 to nearly 50,000 in 2006 and 54,000 in 2007. It fell to nearly 40,000 last year, as violence declined.

The problems facing efforts to collect data in Iraq have been compounded by a brutal insurgency that has prevented on-the-scene reporting through much of the war.

The US and Iraqi militaries also often challenge reports of damage from car bombings, kidnappings, and execution-style shootings, as well as US airstrikes when they suggest security failures. The Shi'ite-led government barred Iraq's Health Ministry from releasing figures in mid-2006 after reports began to show Iraqi civilians dying at a rate of about 100 a day in sectarian attacks.

Many deaths also are likely to go unreported, as families bury loved ones before sundown on the day of the death to comply with Muslim tradition.