Media type: E-Article Title: Impact and Costs of Incentives to Reduce Attrition in Online Trials: Two Randomized Controlled Trials Contributor: Khadjesari, Zarnie; Murray, Elizabeth; Kalaitzaki, Eleftheria; White, Ian R; McCambridge, Jim; Thompson, Simon G; Wallace, Paul; Godfrey, Christine Published: JMIR Publications Inc., 2011 Published in: Journal of Medical Internet Research Extent: e26 Language: English DOI: 10.2196/jmir.1523 ISSN: 1438-8871 Keywords: Health Informatics Footnote: Access State: Open Access