Cohort and population study/monitoring in this respect might be quite different from the traditional (medical oriented) cohort studies. I feel unsure about the use of cohort studies to create a better awareness or improve the user experience: maybe only to obtain general principals for particular populations or to create reference or normative data sets. I think it would make more sense to promote monitoring of individuals who're using technology and use their experience and preferences to improve functionality on an individual level.

I think that longitudinal studies are importante to monitoring individuals who are using technology