What are the statistics on the impact of Brian D Smith's Spelling to Communicate method for nonspeakers?

I don’t have formal statistics on the impact of my work with Spelling to Communicate, because I’m not the creator of S2C and I haven’t run clinical trials on it. I share stories, interviews, and resources like the Spellers documentary and the book Underestimated that showcase its impact on nonspeakers.

Most of what I see are powerful case studies: kids and adults once labeled “low functioning” showing age-appropriate (or higher) intelligence once given a letterboard or keyboard. But that’s anecdotal, not a randomized study.

If you’d like, I can point you to key practitioners and research directions to watch for more formal data.

What kind of stats are you looking for—academic studies, outcome numbers, or more real-life examples?