title: Does self-selection affect samples' representativeness in online surveys? An investigation in online video game research.
abstract: BACKGROUND
  The number of medical studies performed through online surveys has increased dramatically in recent years. Despite their numerous advantages (eg, sample size, facilitated access to individuals presenting stigmatizing issues), selection bias may exist in online surveys. However, evidence on the representativeness of self-selected samples in online studies is patchy.
  
  
  OBJECTIVE
  Our objective was to explore the representativeness of a self-selected sample of online gamers using online players' virtual characters (avatars).
  
  
  METHODS
  All avatars belonged to individuals playing World of Warcraft (WoW), currently the most widely used online game. Avatars' characteristics were defined using various games' scores, reported on the WoW's official website, and two self-selected samples from previous studies were compared with a randomly selected sample of avatars.
  
  
  RESULTS
  We used scores linked to 1240 avatars (762 from the self-selected samples and 478 from the random sample). The two self-selected samples of avatars had higher scores on most of the assessed variables (except for guild membership and exploration). Furthermore, some guilds were overrepresented in the self-selected samples.
  
  
  CONCLUSIONS
  Our results suggest that more proficient players or players more involved in the game may be more likely to participate in online surveys. Caution is needed in the interpretation of studies based on online surveys that used a self-selection recruitment procedure. Epidemiological evidence on the reduced representativeness of sample of online surveys is warranted.
authors.affiliation: Geneva University Hospitals, Geneva, Switzerland. yasser.khazaal@hcuge.ch.
authors.forename: Yasser
authors.initials: Y
authors.lastname: Khazaal
authors.forename: Mathias
authors.initials: M
authors.lastname: van Singer
authors.forename: Anne
authors.initials: A
authors.lastname: Chatton
authors.forename: Sophia
authors.initials: S
authors.lastname: Achab
authors.forename: Daniele
authors.initials: D
authors.lastname: Zullino
authors.forename: Stephane
authors.initials: S
authors.lastname: Rothen
authors.forename: Riaz
authors.initials: R
authors.lastname: Khan
authors.forename: Joel
authors.initials: J
authors.lastname: Billieux
authors.forename: Gabriel
authors.initials: G
authors.lastname: Thorens
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D003198:Computer Simulation; D003625:Data Collection / Q000379:methods* / Q000706:statistics & numerical data; D006801:Humans; D020407:Internet; D008297:Male; D018910:Video Games
keywords: Internet; World of Warcraft; bias; massively multiplayer online role-playing; online survey; random sample; self-selection