eHealth research and evaluation: challenges and opportunities.
D000293:Adolescent; D016494:Computer Security; D003219:Confidentiality; D004059:Diffusion of Innovation; D006266:Health Education / Q000379:methods / Q000592:standards; D006302:Health Services Research; D006801:Humans; D007255:Information Services / Q000592:standards*; D020407:Internet; D017063:Outcome Assessment, Health Care; D019460:Tobacco Industry; D014481:United States