Data cleaning began during the data collection process. Inputs for the cleaning process include available interviewers’ note following each question item, interviewers’ note at the end of the tablet form as well as supervisors’ note during monitoring. The data cleaning process was conducted in following steps:
• Append households interviewed in ethnic minority languages with the main dataset interviewed in Vietnamese.
• Remove unnecessary variables which were automatically calculated by SurveyCTO
• Remove household duplicates in the dataset where the same form is submitted more than once.
• Remove observations of households which were not supposed to be interviewed following the identified replacement procedure.
• Format variables as their object type (string, integer, decimal, etc.)
• Read through interviewers’ note and make adjustment accordingly. During interviews, whenever interviewers find it difficult to choose a correct code, they are recommended to choose the most appropriate one and write down respondents’ answer in detail so that the survey management team will justify and make a decision which code is best suitable for such answer.
• Correct data based on supervisors’ note where enumerators entered wrong code.
• Recode answer option “Other, please specify”. This option is usually followed by a blank line allowing enumerators to type or write texts to specify the answer. The data cleaning team checked thoroughly this type of answers to decide whether each answer needed recoding into one of the available categories or just keep the answer originally recorded. In some cases, that answer could be assigned a completely new code if it appeared many times in the survey dataset.
• Examine data accuracy of outlier values, defined as values that lie outside both 5th and 95th percentiles, by listening to interview recordings.
• Final check on matching main dataset with different sections, where information is asked on individual level, are kept in separate data files and in long form.
• Label variables using the full question text.
• Label variable values where necessary.
