Gary Langer de ABC fait état d'une recherche menée pour le U.S. Census Bureau comparant les résultats d'un sondage Internet et d'un sondage téléphonique. Ca donne ceci:
Blog Gary Langer ABC News sur les sondages internet de type panel
- “The telephone samples were more demographically representative of the nation’s population than were the Internet samples after post-stratification.”
- On attitudinal questions, the proportions of most-common responses in the two datasets differed by 13 points on average and more than 30 points in some cases.
- “This investigation revealed systematic and often sizable differences between probability sample telephone data and non-probability internet data in terms of demographic representativeness of the samples, the proportion of respondents reporting various opinions and behaviors, the predictors of intent to complete the Census form and actual completion of the form, changes over time in responses, and relations between variables.”
De grâce, ne tirez pas sur le messager, c'est pas de ma faute!