Data Validation

Validation prevents invalid data from being entered. Examples:

Benefits include:

• Reduced cleaning effort
• Improved accuracy
• Better compliance

Validation should be implemented whenever possible rather than relying on later cleaning.

Branching Logic

Branching Logic displays fields only when relevant. Example: Question: “Has participant ever been pregnant?” If No: Hide pregnancy questions. If Yes: Show pregnancy history section. 4 Example syntax: [pregnant_history] = ‘1’ This means the associated field appears only when pregnancy history equals Yes. Branching logic improves:

• User experience
• Data quality
• Form completion speed

Calculated Fields

Calculated fields derive values automatically. Examples:

Body Mass Index

([weight_kg])/(([height_cm]/100)^2)

Age at Enrollment

datediff([dob],[enrollment_date],”y”)

Although REDCap can calculate values during entry, important derived variables should still be reproduced during statistical analysis to ensure reproducibility.

Longitudinal Design

Many clinical studies collect repeated observations.

Example:

REDCap allows:

• Event creation
• Instrument-event mapping
• Scheduling
• Repeat measurements

Longitudinal functionality must be enabled in project settings before events can be configured.

 Repeating Instruments

Repeating instruments are useful when the number of observations is unknown.

Examples:

Adverse Events

One participant may have:

• Zero events
• One event
• Twenty events

Medications

Participants may receive multiple drugs.

Laboratory Samples

Multiple specimens collected at different times.

Repeating instruments avoid creation of large numbers of unnecessary variables