title: [An observational study requires careful consideration by the reader].
abstract: The observational study has its merits when randomized controlled studies are impossible to perform. This review discusses its merits and weaknesses for a reader of such studies. The reader has to consider the internal and external validity of the study and its role in the establishment of causal relationships and estimations of risks. The reader is recommended to primarily evaluate the quality of study design, confounding and measurement bias, rather than to try to understand if an advanced statistical analysis is correct. The possibilities of misleading results are discussed.
authors.affiliation: Institutionen för folkhälsa och klinisk medicin, Umeå universitet, yrkes- och miljömedicinska kliniken, Norrlands Universitetssjukhus, Umeå. bengt.jarvholm@envmed.umu.se
authors.forename: B
authors.initials: B
authors.lastname: Järvholm
mesh_terms: D015982:Bias; D015984:Causality; D003627:Data Interpretation, Statistical; D005069:Evaluation Studies as Topic; D019317:Evidence-Based Medicine; D006801:Humans; D019370:Observation; D015588:Observer Variation; D016032:Randomized Controlled Trials as Topic
vernacular_title: En observationsstudie kräver grundlig eftertanke av läsaren.