The federal government does not have a Department of Statistics. Instead it's decentralized to each agency.
There used to be a couple of useful places that offered statistics from all the agencies, the Census Bureau's Statistical Abstract and the website FedStats. But the Statistical Abstract, a publication that has been around since 1878(!) was eliminated because of budget cuts in 2011. A private publisher now compiles the statistical tables. And FedStats, which used to have an awful interface but at least was keyword searchable, now simply gives you links to all the agencies that compile statistics.
So rather than searching FedStats, use USA.gov to figure out what agency cares about a particular issue, then skim the agency's website for statistics.