# Introduction

There was a time when researchers had direct access to their home hospital's electronic health record (EHR). Data were only available to researchers for hospital(s) that were affiliated with academic institutions that employed them. In many cases, EHR data and their associated databases could only be accessed onsite. Often, data from ancillary services, such as pharmacy and laboratory data, outside of the hospital, were inaccessible. If the needed data were part of a hospital information system module that had not been created yet, it was considered impossible to access and required manual chart review.

Over the years, researchers built systems and modules to enhance the collection of data for patient care, and eventually fuel additional "secondary data" research. Nationally, biomedical informatics visionaries pointed the way and guided us in how to make research dreams into realities. There were many successes, and as many failures to achieve the vision of researchers having untethered access to EHR and other health data. The eventual result of these trials and tribulations is now a new world of health system-wide data warehouses, secure research enclaves, federated research networks, statewide health information exchanges, all-payer claims databases, and national health data repositories. The term “big data” seems diminutive now that we can leverage trillions points of health data for our research across the nation \[[1](#references)].

Observational Health Research has come of age in terms of data and the tools to conduct research. There is still much work to be done in terms of [**Health Research Data Governance**](https://docs.bcbi.brown.edu/codiac-for-health/foundations/health-research-data-governance) structures, policies, and procedures. As CODIAC for Health grows and evolves, this chapter will be enhanced to serve as your go-to for the "whys," "whats," and "hows" of it all.

## References

1. Butte A. [**Precisely practicing medicine with a trillion points of data**](https://www.youtube.com/watch?v=fbZZ_1Jbm6w). TEDxSanFrancisco. 2017.

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