Yeah because it’s primary research and this is a huge unaddressed and uncared about problem that’s only growing. The last National Assessment for Adult Literacy took place in 2003.

PIAAC (PROGRAM FOR THE INTERNATIONAL ASSESSMENT OF ADULT COMPETENCIES) which this is likely partially based on is typically who provides the survey data to these institutions.

Barbara Bush Foundation is another source that deals specifically with this.

A lot of this data is cobbled together because the government has practically defunded any studies of this issue. Literacy has effectively been taken for granted and hasn’t actually been upheld. Everyone in this space says more data is needed but isn’t optimistic that more data is going to paint a better picture of literacy (both in children and adults) in the US.