Just when we need reliable information the most, the data is at risk of giving misleading signals.

“We have several different types of policies all bundled together, and we’re going to be looking for insights as to which of these policies are working and which ones to reinforce,” said Tara Sinclair, a senior fellow at Indeed Hiring Lab and a George Washington University economist who studies business cycles. “The shutting down of large parts of the economy was not anticipated in the construction of our economic statistics.”

Consider the unemployment rate.

It is based on a monthly survey of 60,000 American households, conducted by the Census Bureau and the Bureau of Labor Statistics. Survey takers first visit randomly selected homes to ask the people living there to participate; in subsequent months they are contacted by phone.

But in-person visits ceased on March 20 to protect the health of survey takers, according to a document published by the B.L.S. to explain potential coronavirus-related effects to the March data. The response rate of Americans contacted fell by 10 percentage points for those set to be contacted by phone and 20 percentage points for those who were to be contacted in person.

“These data collectors are very professional people, and they will be doing everything they can to reach out to these households,” said Katharine Abraham, a former commissioner of the B.L.S. and an economist at the University of Maryland. “But they’re handicapped if they can’t go out and knock on the door.”

This could distort results, for example, if the people still working are more likely to ignore requests to be included in the survey than those who are stuck at home unemployed.