Less than a week ago, President Obama announced a policy change that could affect as many as 1.4 million young undocumented students living in the United States by halting their deportation proceedings and granting them temporary work permits. However, figuring out who is eligible under Obama’s new policy, and how many of them exist, has been no easy task.

Pew Hispanic Center associate director Mark Hugo Lopez explained that measuring an undocumented population is inherently challenging and estimates can therefore vary widely.

“There are no surveys which ask people, ‘Are you here in the country illegally or not?’ And if there were, I’m not sure how reliable responses would be. So we have to rely on a number of different existing sources,” Lopez told The Huffington Post.

Obama’s directive will reportedly affect many of those undocumented immigrants — often termed DREAMers — who would have benefitted under a decade-old bill called the Dream Act, last struck down in 2010. The new policy includes those living in the country under the age of 31 who came to the U.S. as children; who don’t have a criminal record; and who have served in the military, or are currently attending, or have graduated from, high school or college.

The Department of Homeland security estimated on the day of the policy announcement that nearly 800,000 individuals would be affected. However, the Pew Hispanic Center and Migration Policy Institute have independently given a number almost twice the size, projecting that nearly 1.4 million individuals will be affected.

Read the full story at The Huffington Post