by PatientsLikeMe use the site. Heywood responded that 20 percent of the ALS patients who were diagnosed in the United States within the last six months joined PatientsLikeMe. “We have about 11 percent of the U.S. ALS population in the website right now, and of those, about 60 percent are giving us what we call a clinical-trial-a-year’s worth of data.” Josh Sommer added that about one-fifth to one-quarter of all U.S. chordoma patients are represented in the Chordoma Foundation database. Heywood noted that “there is a minimum scale of about 500 patients that we find needed to get an effective dialogue going, and there appears to be a ceiling of about 11,000 to 12,000 patients within a single community that we need to figure out how to break through with our current information architecture.” Heywood implied that the high degree of dialogue that occurs on some sites limits the number of people that can effectively participate in them. Dr. Sommer also noted generational differences, with older individuals perhaps not as willing to be open and share everything online as the younger generation (e.g., on Facebook).