Demographic and Health Surveys Methodology - Measure DHS

it is not possible to merge the household and women’s files using HHID and CASEID because CASEIDhas three extra characters identifying the women’s line number. The files can be more easily mergedusing variables HV001 with V001 and HV002 with V002.RelationshipsWhen merging data files it’s important to know the type of relationship that exists between the files to bemerged as well as the type of output file desired (unit of analysis). There are two types of relationships:The first is that of one entity related to many other entities [1 : 0-N] and the second is that of one entityrelated to just one other entity [1 : 0-1]. An example of a relationship of one to many entities can be foundbetween households and women or men. There may exist zero or several women or men questionnairesfor each household (see structure figure at the beginning of the document). An example of a relationshipof one to one can be found in the relation existent between women and men. In a monogamous country,there may be zero or one man questionnaire for each woman if she is currently married.All statistical packages (SPSS, SAS, STATA) have commands that allow merging files, but regardless ofthe package the following steps are necessary:• Determine the common identifiers (identification variables).• Sort both data files by the identification variables.• Determine the base (primary) file. The base file essentially establishes the unit of analysis.- Normally, when the relationship is that of one too many [1:0-N], the base file is the one with themany entities. For example, if merging data from households and women, the base file should bethe women’s file. The reason is that you may want to assign to every woman the characteristics ofher household. If the match is done the other way around, once the program matches the firstwoman it will not look for another woman or it will give an error for finding duplicate cases. In thecase of matching women and children, the base file should be the children’s file. That way,mothers’ characteristics are assigned to children.- If the relationship is that of one to one [1:0-1], the base file is normally the one with the leastnumber of cases. In DHS, male questionnaires are only applied to a subsample of households. Thismeans that not all currently married women have a match with a male questionnaire. In this case,the base file should the male questionnaire and the resulting file (unit of analysis) will be theCouples file.• Finally, using the right commands depending on the software to be used, the files will be merged.The following table shows the variables required to match different files. In the rows, the base files arelisted. In the columns, the secondary files along with the variables to be used as keys or matchingvariables are listed. In the cells intersecting the rows and columns, variables from the base files used tomatch the secondary file are listed.Matching VariablesSecondary FilesBaseMatch variables for HouseholdsHV001 + HV002Match Variables for womenV001 + V002 + V003Women V001 + V002Children V001 + V002 V001 + V002 + V003Men MV001 + MV002 CouplesMV001 + MV002 + MV034iGuide to DHS Statistics 22 September 2003