We found a matchYour institution may have access to this item. Find your institution then sign in to continue.TitleObservational studies of treatment effectiveness: useful, useless or somewhere in between?AuthorsMarrie RAPublicationMultiple sclerosis (Houndmills, Basingstoke, England), 2013, Vol 19, Issue 6, p707ISSN1352-4585Publication typearticleDOI10.1177/1352458512465136