When Mayor Giuliani officially declares his bid for the presidency in the coming weeks, his campaign will rest largely on the historic drops in crime levels New York City experienced during his time as mayor.

Those decreases came with the infusion of thousands of new police officers and, more famously, the invention of a management tool called Compstat, which uses data about crime to respond to trends and hold commanders accountable for the conditions of their precincts.

(Criminologists say the retreating tide of crack cocaine addiction and other social factors also helped push down crime.)

Mr. Giuliani’s political boast couldn’t come at a more opportune time, observers said. Not only has a Compstat-like system spread to nearly every agency of the municipal government in New York and other cities such as Baltimore, but there are also movements in Albany and Washington, D.C., to run more of government by its standards of accountability.

“Most people assume being mayor of New York is a detriment for Rudy Giuliani running,” a biographer of Mr. Giuliani, Fred Siegel, said. “But City Hall is where people are accomplishing and not merely engaged in endless partisan recrimination. … People know something fundamentally changed in New York” during the Giuliani administration.

Mr. Giuliani’s police commissioner, William Bratton, and his deputy commissioner of strategic initiatives, Jack Maple, hit on the idea of Compstat as they searched for ways to turn around crime trends that were tormenting New Yorkers in the 1990s. There were 2,245 murders in the city in 1990. Last year, less than 600 people were murdered, and crime in the major categories is at the lowest levels in decades.

After Mr. Giuliani got rid of Mr. Bratton (the speculation was that the commissioner was stealing the spotlight with his success at fighting crime), he not only kept Compstat but also gave other city agencies a six-month deadline to come up with their own versions of the management system.

Mayor Bloomberg has continued this tradition. In the wake of the Nixzmary Brown case, the Administration for Children’s Services has created ChildStat to track the outcomes of child abuse cases. The Department of Consumer Affairs has created CultureStat to measure each cultural institution’s performance.

“You may be asking yourself: ‘Didn’t people always do that?'” a professor at New York University’s Wagner School of Public Service, Dennis Smith, asked his management class last week. “The answer is no. This is recent.”

The guest speakers were two commissioners of city agencies with Compstat success stories, Martin Horn of the Department of Correction and Iris Weinshall of the Department of Transportation.

Mr. Horn showed slides of his department’s improvements under the system, called the Total Efficiency Accountability Management System. Slashings and stabbings in the jails decreased to 37 in fiscal 2006 from 1,093 in fiscal 1995, and sick days were reduced to about 12 days an employee from about 20 days in the same period, he said.

“This is about getting people to do their jobs, and do their jobs better,” he said.

Mr. Smith has spent more than a decade of his career studying Compstat and its development into what he now calls “performance management.” Along the way, he has taught the method — accurate and timely intelligence, rapid deployment, effective tactics, and relentless follow-up — to his classes. Many of these students, including Mr. Horn, now hold government positions in the city, state, and federal government.

The shift before and after Compstat was simple, but far-reaching in its consequences, Mr. Smith said. The city stopped measuring what it was doing and started measuring the outcome. Using that information, which is collected and tabulated by technology now accessible in the field as well as at headquarters, agencies are better positioned to hold managers responsible and come up with solutions to seemingly intractable problems.

“If we map out the logic of how we’re going to get to that greater tomorrow, then we can set milestones to see how we’re making progress on achieving those policies,” Mr. Smith said.

When Governor Spitzer was elected, one of the first promises he made regarding his administration was “regular and rigorous evaluations of executive agencies, including that agencies adopt performance measurements.”

Already, Mr. Smith has been approached by three state commissioners for advice about developing a Compstat-like system for their agencies, he said.

“Measuring results is a standard practice in the private sector,” the director of research at the Business Council of New York State, Robert Ward, said. “It should be the standard practice in the business sector as well. New York City is a leader, but local governments across the country are laggards. It’s starting to spread.”

A former speaker of the House, Newt Gingrich, is also a proponent of the system. In an interview this week, he said the rest of the country could learn valuable lessons from New York City’s successes during the last decade.

“I talk about it virtually everywhere I go,” he said. “If crime is a significant concern, and it should be, then New York is the most successful experiment in saving people’s lives and stopping crime in modern times.”

Mr. Gingrich said that since 2005 he has been advocating inside the Department of Defense, State Department, and the White House for Compstat to be used to “manage projects like Iraq and Afghanistan.”

According to a 2004 study by the Police Foundation, 32.6% of 445 police departments with 100 or more sworn officers in the United States have Compstat-like systems. An additional 25.6% said they were planning to bring in such a system.