Nearly 900,000: That’s how many infants, toddlers and preschoolers are in Los Angeles County right now.

Disturbingly little is known about the circumstances of these most vulnerable members of the community. Many are at home, but others are in child care centers and preschools that run the gamut from high quality to abysmally low quality.

Troubled by so much uncertainty, Jacquelyn McCroskey wanted to help.

“I’ve been thinking about what academics have to offer in this,” the USC social work professor said. A longtime advocate for better child services, she had the bright idea of pooling existing information.

California has four separate programs funneling state subsidies to licensed child care providers. There are also nine state-funded child care resource and referral agencies in Los Angeles County, home of the nation’s largest federally funded Head Start program.

“All these government agencies gather a lot of administrative data, which they use primarily internally,” said McCroskey, John Milner Professor of Child Welfare at the USC School of Social Work.

What these bureaucrats rarely do is share information.

“But if you can figure out a way to go across the silos,” McCroskey realized, “you can actually say things that are pretty surprising to people who generally only focus within their areas.”

An expert in child welfare, juvenile justice and early childhood education, McCroskey has contacts in all of these agencies. Through her affiliation with the First 5 LA Board of Commissioners, she helped form the Los Angeles Children’s Data Network two years ago and has systematically set about aggregating cross-agency data.

“It wasn’t easy to get all these people to work together and share their stuff,” she said. “But once you did that, you could really see that the geographic impact [of child care budget cuts] was very different in different parts of Los Angeles County.”

In April 2012, the data network issued “Shrinking Investments Yield Smaller Returns,” a report that paints a grim picture of decline. Between 2008 and 2011, the elimination of $1.2 billion in state funds earmarked for early child care and education resulted in the loss of more than 11,200 “seats” for low-income children. In December, McCroskey spearheaded Save My Seat, an interactive website detailing the loss of seats by age and income status. The data is also searchable by ZIP code, city, school district and legislative and congressional district. The project prompted an article in the Los Angeles Times.

Thus, data point by data point, McCroskey is connecting the dots, bringing together stakeholders and holding county authorities accountable.