Abstract
Since the telephone (RDD) poll of the day is carried out in the call center, which is highly managed, the risk of operator's error generation is low.
However, this report suggests the risk of operator's error generation due to intervene of operator's judgment. It is the case that the questionnaire is not carefully examined.
Now therefore, the question with an unclear meaning with a long sentence and/or an open-answer question must be avoided when there is not enough time for developing a thorough questionnaire.
