Community policing is a delicate and constantly evolving concept as well as a long-standing focus for the NYPD.

Future Commissioner James O’Neill has been dubbed the “architect” of neighborhood policing, with Mayor Bill de Blasio’s full support. But the idea of community policing, what exactly it means and how it is carried out, as well as the effectiveness of it, remains open for interpretation.

The concept has been referred to by experts as the “old way” of policing, hearkening back to a time before the controversy of quotas, the stop-and-frisk era, and several high-profile fatal police-involved shootings that catapulted both the city and the nation into conflict.

The NYPD first established precinct community councils — meetings at which the public can meet the officers in their neighborhood and voice any concerns — in the 1940s. Most recently, the department expanded its Neighborhood Coordination Officers program to 51 percent of commands in the hope that New Yorkers get used to seeing the same officers in the same places every day.

Here’s a look at where the effort is now, and what measures department officials are looking at to assess the effectiveness of the program.

What is the Neighborhood Coordination Officers program?

Under the Neighborhood Coordination Officers program, two officers are posted to the same spot at the same time each day with the aim of establishing a relationship with those in the community they serve.

These officers also have medical training to improve conflict resolution skills, according to the department.

“The cops are embracing it,” O’Neill said recently at police headquarters. “We have a lot of work to do. Cops sometimes have a difficult time with change ... but this change is a good change. It’s a good change for the city, and it’s definitely a good change for the police officers because we’re pushing that decision-making down to the level where it should be.

“We’re enabling them to use discretion, which they should use,” he added.

O’Neill said the program is a “crime-fighting model” and added that it seems to be working.

The total number of NCOs in a given command depends on the size of the precinct.

Where is it being implemented?

The program first started in four precincts in May 2015, including in Washington Heights and Inwood in Manhattan, and parts of Rockaway in Queens. The program was then expanded to 32 total precincts.

In October, the program will get another boost, growing to include 12 more precincts (or 51 percent of all commands and all housing commands).

The new NCO program includes the East Village and Harlem in Manhattan, Jamaica and Astoria in Queens, and Brooklyn Heights and Coney Island in Brooklyn.

How can you measure its effectiveness?

De Blasio said there is both “tangible” and “intangible” measures of community policing: an example of the former being a crime that was prevented by someone trusting an NCO to tell them about it, and the latter being the concept of the relationship between the police and the community they serve.

“We know that we will become safer as we bond police and community,” he said. “And that is an everyday effort. So every single time a community member has a good experience with a police officer, a communicative experience, it’s going to want to make them come back and share more information, they’re going to tell their family, they’re going to tell their neighbors.

“This is something that changes the whole tone of this city over time,” de Blasio added. “The more there’s an assumption that everybody’s on the same team, the more progress we can make.”

In terms of what has already been measured, O’Neill said that in NCO commands, the murder rate is down 5.6 percent as of July 31, slightly more than the citywide rate, which is down by about 4 percent compared with last year. Robberies are down 5.8 percent, he said.

O’Neill said that response times have also decreased this year: the time it takes to respond to a critical crime, or one of the seven major felonies, in progress has gone down by 30 seconds for the first seven months of this year, compared with a response time of 5 minutes during the same period last year.

“I had an idea with the neighborhood police model that it would reduce crime response times, but not to the level of this,” O’Neill said.

The department will continue to measure the 311 and 911 calls.

“The more we get to know the people in the community, if there is a chronic 311 we should be able to resolve that,” he said.

What will the NYPD do in the future?

Police Commissioner Bill Bratton said recently that the department plans to get into the business of polling — on average 20,000 people at a time.

This will be done on “almost to the block level of every precinct” as well as polling officers.

“No American police department has ever had the resources to poll — how are we doing? And we are going to do it for the first time in the history of this country, we’re going to do it a larger scale than just about any poll that you’re used to.

“It’s going to be extraordinary,” he added.