Chapter Data Cleaning 2.1 Reasons Follow up data can not be sent immediately to the processing and analysis because of the many errors: • The quality of the interview: Interviewer misunderstood questionnaire, interviewers collected incorrect information, write to the wrong questionnaire • Input: false, shortcomings, redundant 2.2 Measures to prevent • Design a questionnaire clear, easy to understand, easy to answer • Selection and training of interviewers carefully Interview a few tests before the interview so to avoid errors • The questionnaire after the interview must be read check error control, edit before entering 2.3 Methods of Data Cleaning • Use a frequency table • Use a table combination of two or three variables • Use the Data-> Select case to filter out the case of an error • Combined with a program excel ... misunderstood questionnaire, interviewers collected incorrect information, write to the wrong questionnaire • Input: false, shortcomings, redundant 2. 2 Measures to prevent • Design a questionnaire clear,... carefully Interview a few tests before the interview so to avoid errors • The questionnaire after the interview must be read check error control, edit before entering 2. 3 Methods of Data Cleaning.. .2. 1 Reasons Follow up data can not be sent immediately to the processing and analysis because of