There are rapid changes in social and survey surroundings since the Population and Housing Census of Korea has started in 1960. Especially, internet survey newly adpated to the 2010 Census does main role in questionnaire redesign. Internet survey as self-administered way is a different mode compared to face to face interviewing which is main way to collect the Census data.

As needs for questionnaire chage grow, the Census Division decided to redesign questionnaire toward user friendly. Statistical Research Institute identified problems using three common pretesting methods such as cognitive interviewing, interviewer debriefing, field test and suggested a new questionnaire version. This paper compares the results of three pretesting methods and offers some conclusions about the effectiveness of using each these methods.