Ever feel like your phone has been spying on you? Maybe you were talking to friends about a potential vacation destination, for example, and then you start seeing ads in your social media feed about the place you were just talking about.

Your phone probably was listening to you, and key bits of your conversation found their way into a profiling database maintained by a market research firm. These firms purchase your data from your cell provider and combine it with other data they’ve compiled on you from various other sources, including all those “cookies” that you absentmindedly accept when browsing online. They then create demographic and economic profiles that they can sell to advertisers, who are seeking to efficiently target potential customers.

Most people don’t like the idea of anonymous corporations compiling data about them. But at least these corporations are doing it with a straightforward motive — to sell you goods and services that they think you’ll want.

But what if it were the United States government assembling your data and profiling you? Why might they want to do this?

Piecing together data from disparate sources is not necessarily a nefarious exercise. As a frequent user of U.S. Census Bureau data in my current job, I can attest to the power of combining data items from multiple surveys and programs to create a more comprehensive picture of an issue than any individual dataset can tell us on its own. For example, linking data on population density with data on vehicle ownership for the same geographical areas can reveal a pattern in which people who live in places with higher densities, where destinations are closer together, tend to need fewer vehicles. But you don’t see this picture until you put the pieces together.

At the same time, as a former Census Bureau employee, where data confidentiality was among the issues I worked on, I am alert to the downsides of interagency data sharing. People and organizations are more likely to provide federal agencies with information about sensitive topics if they feel assured the agency is not going to share their information with other parts of the government with unrelated missions, particularly those with a law enforcement responsibility. To this end, agencies charged with collecting and maintaining data make promises of confidentiality to their respondents (the Census Bureau’s is known as Title 13), and they take their role as data custodians seriously, impressing upon each new employee the importance of this promise.

The unauthorized harvesting and assembly of data from multiple federal agencies — including the Social Security Administration and the Internal Revenue Service, among others — by the “Department of Government Efficiency” (DOGE) is thus cause for serious concern. What does DOGE — and now also, apparently, Palantir, a private contractor — want with all that personal data in one place, beyond the needs articulated by the agencies individually authorized to collect it? The Trump administration may initially claim it is using this database to track and apprehend illegal immigrants, for example. But it could just as easily be deployed to retaliate against perceived political enemies or to construct a surveillance state to monitor political dissenters. Such a powerful tool could be used for much more than just trying to sell us things.

Unease about why the administration might be seeking to assemble a master database about American people and businesses — and a lack of clear guidelines as to who would be authorized to use it — undermines the promises that statistical agencies make to their respondents to keep their data confidential. Growing mistrust will gradually corrode each agency’s ability to collect reliable data, compromising their ability to produce accurate information about our society and economy.

The degradation of federal data is everyone’s problem, because all kinds of federal, state and local agencies depend on it to make efficient regulatory decisions, to provide important services to the people who need them and to invest in the future. Academic institutions and nonprofit researchers (like New Jersey Future) can’t identify and measure problems without reliable federal government data.

Do we want to know how many people are leaving New Jersey to move to other states? We need the Census Bureau’s annual population estimates for that. Perhaps we suspect that unaffordable housing prices might be a driver of out-migration, and we want to know which towns offer the widest variety of housing options for both homeowners and renters. We need the Census Bureau’s American Community Survey to get that data.

An erosion of trust in federal data collection efforts, compounded by indiscriminate staffing cuts at the Census Bureau, could affect even the basic task of counting everyone every 10 years, especially in states like New Jersey with large numbers of historically hard-to-count sub-populations like immigrants and lower-income renters. Because many federal programs distribute funds to states on a per-capita basis, an inaccurate head count could result in New Jersey receiving less federal aid than it would otherwise be entitled to, and could even lead to a shortfall in congressional representation, the linchpin of our representative democracy.

When we think of what the federal government does, we think of the military, Medicare and dozens of other more visible functions. Most of us never think of the gathering, use and protection of data. But if the federal government doesn’t have data, many critical functions fail. And if that data is abused, it poses a danger to all of us.

What you can do: Stay informed. Understand how government data is collected, shared, and protected, and why it matters. Tell your friends and family why it matters. And ask your elected officials in Congress where they stand on safeguarding federal data and protecting the agencies that produce it.