1. Representativeness and qualityof online sampling German Loewe Founder & CEO

4. Unknown error

5. Representation via quotasQUOTA SAMPLING Main sampling techniques

6. Sample Frame Sample Frame exists = target population 1 Units sampled randomly (known distribution) 2 The three pillars of representativity… Target Population Population

7. Sample Frame Sample Frame exists = target population 1 Units sampled randomly (known distribution) 2 Unbiased non-response 3 The three pillars of representativity… Target Population Population

8. Internet Population Target Population Population No such thing as a Sample Frame exists 1 …no random (unknown inclusion probabilities) 2 …also non-response 3 Online’s methodological limbo…

10. low response rates

12. low response rates

14. Cheap

15. Multimedia

16. Low incidence

17. Coverage??

18. no sampleframesavailable

19. low response rates

21. Cheap??

22. Multimedia??

23. Low incidence?

24. Coverage

25. no sampleframesavailable

26. low response rates

27. no time / money for designOff-line

28. How big is the coverage disadvantage? ? On-line Off-line

30. Not visiting web sites were you recruit

31. Not wanting to participate in on-line surveys

33. Not visiting places were you recruit

34. Not wanting to participate in off-line surveys

35. Abandoning off-line surveys longer than Y minOff-line

37. Not visiting web sites were you recruit

38. Not wanting to participate in on-line surveys

40. Not visiting places were you recruit / not at home

41. Not wanting to participate in off-line surveys

42. Abandoning off-line surveys longer than Y minOff-line

44. Not visiting web sites were you recruit

45. Not wanting to participate in on-line surveys

47. Not visiting places were you recruit / not at home

48. Not wanting to participate in off-line surveys

49. Abandoning on-line surveys longer than Y minOff-line

51. Not visiting web sites were you recruit

52. Not wanting to participate in on-line surveys

54. Not visiting places were you recruit / not at home

55. Not wanting to participate in off-line surveys

56. Abandoning off-line surveys longer than Y minOff-line

57. DEPENDS ON: Typeofproductorserviceyou are askingabout: A PDA device? Oran ice cream? So how much should you worry about coverage?

58. Measurement Error 4 PROBABILITY SAMPLING …what about the measurement error? 1 2 Coverage Error Sampling Error “Sample Frame does not match target population” Statistical error (under control) 3 Interviewer Mode-effects Social desirability Situational representativity Control via technology Non-response “Only people wanting to share opinions participate” Online ok!!!

60. No monetary incentives

61. Maximum 2-3 surveys a month (different categories)

62. Updated information

63. Continuous automatic updates (mandatory)

64. No fraud

65. Lower duplicates thanks to no media buying

67. Actively recruited only panelists

68. Incentivize recruiting

69. No incentive or content announcement in the field

71. Incentivize proportional to time (including filter-outs)

73. If you cannot look inside, how can you know find the quality providers?? “It’s the observation rate, stupid”

74. Thankyou! German Loewe gloewe@netquest.es