How many hate crimes have been committed since the election? The short answer is, we don’t know.

National data on hate crime is scarce. The F.B.I. releases annual statistics on hate crimes, but not every incident is reported to the agency. And some incidents of bias-motivated harassment or intimidation don’t fit the F.B.I.’s definition of a hate crime. However, the Southern Poverty Law Center and other groups are studying the problem with an eye to providing more comprehensive data. Below are a few things we know about trends in hate crime before and after the election, false reports and more.

According to the F.B.I., hate crimes rose in 2015.

The F.B.I. hasn’t released hate crime data for 2016 yet, but in November it reported a total of 5,850 hate crimes in 2015, up from 5,479 in 2014. The biggest jump was in anti-Muslim hate crimes, which rose by 67 percent last year. Anti-Semitic crimes were up 9 percent, and anti-black crimes rose almost 8 percent.

Terrorist attacks in the United States and Europe may have stirred up anti-Muslim hatred in 2015, according to the Southern Poverty Law Center. But Donald Trump’s campaign promises about banning Muslims may have played an even bigger role. “Whenever a politician starts attacking a particular population,” said Heidi Beirich, who directs the S.P.L.C.’s yearly count of hate groups, “we tend to get hate crimes.”

The Southern Poverty Law Center has found more than 1,000 reports of hate incidents since the election.