**Why has this project being developed?** At PSEMAU, which is the research group in Psychiatric and Social Epidemiology and Health Metrics from the [Department of Clinical Epidemiology at Aarhus University][1], we use data from administrative registers in Denmark to conduct our research. In an attempt to make our research as open and reproducible as possible, we have developed this project at Open Science Framework to share data documentation and programming code for all data we use in the studies we publish. While the underlying data cannot be made publicly available due to legal and ethical reasons, we hope that our documentation and code might help researchers with access to similar data to (i) replicate our research, (ii) replicate our designs and analyses for other research questions, and (iii) get inspiration on how to transform the raw data into data that can be used for epidemiological studies. **Feel free to use our code for your own research** Anyone is encouraged to use our code if it is useful. Our project is developed under license CC-BY Attribution 4.0 International, which means anyone can freely use our materials as long as this OSF project (and the underlying scientific publication, if possible) is cited. If you have any questions or suggestions, or you identify a mistake in our documentation or code, please contact us at opr@clin.au.dk. [1]: http://www.kea.au.dk