Technical Notes: A.5 Data entry and cleaning
Once all items have been scored, the results are entered into data files using a common international software and format. The software facilitates the checking and correction of data by providing various data consistency checks. The data are then generally sent to a central international data processing center (DPC) for cleaning. The DPC checks that the international data structure is followed; checks the identification system within and between files; corrects single case problems manually; and applies standard cleaning procedures to questionnaire files. Results of the data cleaning process are documented by the DPC. This documentation is shared with the national research coordinator so that specific questions can be addressed. The national research coordinator then provides the DPC with revisions to coding or solutions for anomalies. The DPC will then compile background univariate statistics and preliminary test scores based on classical and Rasch item analyses. For more detailed information on the data entry, cleaning process, and scoring of each assessment, see the appropriate assessment's technical manual.