The common assumption that there is a massive departure of Mexican immigrants from the U.S. because of the economic downturn is not true, according to a RAND Corporation study released today.

The study, published by the online journal Demography, finds that fewer Mexican immigrants returned home in 2008 and 2009 than in the two years prior to the start of the recession.

“The recession in the United States and the global financial crisis did not increase the number of immigrants returning to Mexico,” said Michael Rendall, the study’s lead author and director of the RAND Population Research Center, in a released statement. He added: “Migration in both directions between the United States and Mexico slowed during the recession, but our findings show there was no rush by Mexican immigrants to return home.”

RAND, however, did not collect the data. The study relies on household survey data of 100,000 households collected by the Mexican government and RAND researchers say the current findings are generally consistent with previous studies on migration patterns between Mexico and the U.S. and recessions over the past several decades.

So why wouldn’t Mexican immigrants return to Mexico in a poor U.S. economy? RAND researchers suggest that it’s the “target earner hypothesis,” which rests on the notion that immigrants return to their home country when they’ve earned their planned savings level.

“This theory suggests that immigrants stay in the United States until they have achieved a certain levels of savings, even if they face a period when their earnings drop and employment becomes harder to find,” Rendall said.