A mayor, whether working in a big city or a small one, sees needs every day that would benefit from the investment of public resources. With such opportunities essentially unlimited but resources quite constrained, how should a leader respond?

A comprehensive answer to this question was recently presented when Bloomberg Philanthropies' What Works Cities initiative lanched a certification program that provides much-needed clarity by identifying and endorsing clear, expert-tested indicators of the capacity to use data effectively.

What Works Cities is a two-year-old initiative that provides technical assistance to midsized cities on open data, performance analytics, low-cost evaluations, results-driven contracting and repurposing of resources. In the process of working with 77 cities across the country, the What Works team identified the need for objective guidance and recognition of data practices that are most effective for delivering outcomes for residents. The resulting certification program, which is open to all cities of 30,000 or more regardless of whether they receive What Works Cities assistance, will recognize examples of excellence across 50 criteria and provide a concrete roadmap for cities that are at any point on the data journey.

As part of the launch of the certification program, we looked at the successes of participating cities to highlight exemplars of selected criteria and to showcase the range of city accomplishments using data, including:

Leading with strategic goals: South Bend, Ind., Mayor Pete Buttigieg uses public strategic goal-setting to drive progress for which he remains transparently accountable. The goals unite city work and data efforts around the highest-priority issues for the community, including equity in policing and dealing with vacant properties; for the latter goal, the city was able to address 1,000 vacant properties in 1,000 days.

Driving open data with policy: Seattle reinvigorated its existing open-data portal when it developed and passed an open-data policy last year. The policy-development process enabled the city to understand and codify residents' priorities, which included a desire for strong privacy protections. The policy institutionalizes open-data practices, such as the designation of an "open-data champion" in each department, and provides a community-backed path for the city to move forward.

Inventorying data: Faced with an open-data portal filled with ad-hoc datasets that required manual effort to update, Kansas City Chief Data Officer Eric Roche embarked on a data-inventory effort. The process built relationships across departments and, with a full understanding of data assets, Roche can now develop a strategic plan to open up data according to the city's priorities.

Monitoring contract outcomes: This year, Boston will use new outcome-based contracts for its asphalt resurfacing program. Based on new data collection and contractually-specified desired outcomes, contractors will be evaluated for their performance and not just for completing the job; the highest-performing vendors will be rewarded with additional work. This kind of contracting ensures that the city is spending its resources in a data-informed way and delivering better results for residents.

Managing performance: Louisville's comprehensive culture of performance and innovation originates in its performance management system, LouieStat. Based on what Mayor Greg Fischer calls a "celebration culture" that is focused on fixing problems, LouieStat engages coordinators in each department to analyze data and align work at all levels with the city's strategic goals.

Testing programs with low-cost evaluation: Washington, D.C.'s The Lab @ DC brings scientific talent in-house to apply low-cost evaluation and other evidence-based methods to government. For example, the lab team helped the police department design a randomized distribution of body-worn cameras to police officers, which will enable objective analysis of the cameras' effects.

Repurposing funds to better serve residents: When faced with the need to cut its spending, Jackson, Miss., compared its budget to those of similar cities to identify disproportionate spending and used granular data-driven analysis of programs' effectiveness to make decisions about where to allocate resources. The resulting budget preserved efforts that were producing outcomes while repurposing resources from those that were not.

These success stories exemplify the power of wisely applied city data in some of the core capacities recognized by What Works Cities' certification. For the first time, mayors have a clear outline of what data-driven operational excellence looks like.