Creating Derived Variables
Table 1
Table
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Table 1
Table
Table 1
| Derived variable | Source variables | Rule source | Risk if poorly defined |
|---|---|---|---|
| Age at enrollment | Date of birth, enrollment date | Eligibility criteria or analysis plan | Incorrect eligibility classification |
| Length of stay | Admission date, discharge date | Protocol or clinical definition | Misreported secondary outcome |
| Visit window status | Enrollment date, visit date | Schedule of events | Incorrect assessment of protocol adherence |
| BMI | Weight, height | Clinical measurement guidance | Unit errors or implausible values |
| Outcome status | Multiple endpoint fields | Endpoint charter or protocol | Incorrect primary endpoint classification |