Web services: The information according to the source is presented in a time series and different intervals. Although we can gather data from 1900 to the present, the great majority of the data are a decade old. Similarly, the output format is different: from the data that can be downloaded as spreadsheet, to data visualization on computer screens, these cases require manual gathering procedures and transformation in order to transfer them to data bases.
Active search: There is information that is not directly accessible or usable for different reasons (e.g. it is not of value, unsuitable aggregation level, sensitive information). Therefore, we must make a search and active request for this information at different administrative levels: municipal, district, regional, and national.
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