title: Medical information on the internet: a tool for measuring consumer perception of quality aspects.
abstract: BACKGROUND
  Most of adult Internet users have searched for health information on the Internet. The Internet has become one of the most important sources for health information and treatment advice. In most cases, the information found is not verified with a medical doctor, but judged by the "online-diagnosers" independently. Facing this situation, public health authorities raise concern over the quality of medical information laypersons can find on the Internet.
  
  
  OBJECTIVE
  The objective of the study was aimed at developing a measure to evaluate the credibility of websites that offer medical advice and information. The measure was tested in a quasi-experimental study on two sleeping-disorder websites of different quality.
  
  
  METHODS
  There were 45 survey items for rating the credibility of websites that were tested in a quasi-experimental study with a random assignment of 454 participants to either a high- or a low-quality website exposure. Using principal component analysis, the original items were reduced to 13 and sorted into the factors: trustworthiness, textual deficits of the content, interferences (external links on the Web site), and advertisements. The first two factors focus more on the provided content itself, while the other two describe the embedding of the content into the website. The 45 survey items had been designed previously using exploratory observations and literature research.
  
  
  RESULTS
  The final scale showed adequate power and reliability for all factors. The loadings of the principal component analysis ranged satisfactorily (.644 to .854). Significant differences at P<.001 were found between the low- and high-quality groups. Advertisements on the website were rated as disturbing in both experimental conditions, meaning that they do not differentiate between good and bad information.
  
  
  CONCLUSIONS
  The scale reliably distinguished high- and low-quality of medical advice given on websites.
authors.affiliation: Institute of Communication and Health, University of Lugano, Lugano, Switzerland. arthur.dubowicz@usi.ch.
authors.forename: Arthur
authors.identifier: http://orcid.org/0000-0001-7025-5285
authors.initials: A
authors.lastname: Dubowicz
authors.forename: Peter J
authors.identifier: http://orcid.org/0000-0002-0405-2284
authors.initials: PJ
authors.lastname: Schulz
keywords: Internet intervention; online health information; quality assessment; scale development; sleeping disorders
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