I was quoting Jillio -- you'd need to ask what sources she was using to support her interpretation of the article in this way: "Looks like the deaf kids are on par with the hearing kids." I don't see anything in that article that slices data to show results for deaf kids and support that.
If she's using the "4th grade" reading levels statistics put out by Gallaudet some years ago and comparing those apples with the latest test results for all kids to find them to be "on par", you can find sources for that data in
Gallaudet's research on literacy section. A few other articles you can start with:
Holt, Judith A., Traxler, Carol B., and Allen, Thomas E. 1997. Interpreting the Scores: A User's Guide to the 9th Edition Stanford Achievement Test for Educators of Deaf and Hard-of-Hearing Students. Gallaudet Research Institute Technical Report 97-1. Washington, DC: Gallaudet University.
Gallaudet Research Institute. 1996. Stanford Achievement Test, 9th Edition, Form S, Norms Booklet for Deaf and Hard-of-Hearing Students. (Including Conversions of Raw Score to Scaled Score & Grade Equivalent and Age-based Percentile Ranks for Deaf and Hard-of-Hearing Students.) Washington, DC: Gallaudet University.