An instrument is equivalent to a CRF.

Examples include:

Demographics Form

Variables:

• study_id
• age_years
• sex
• residence

Medical History Form

Variables:

• previous_admissions
• chronic_conditions
• medication_history

Laboratory Form

Variables:

• hb
• malaria_rdt
• culture_result

A recommended practice is to keep each instrument focused on a specific clinical domain.

Poor design:

One instrument containing 300 fields.

Good design:

• Screening
• Enrollment
• Laboratory
• Follow-up
• Outcome

as separate instruments.

Field Types

REDCap provides multiple field types.

Text Box

Used for:

• Names
• IDs
• Comments

Numeric

Used for:

• Weight
• Height
• Laboratory values

Date

Used for:

• Enrollment date
• Visit date

Time

Used for:

• Sample collection time
• Medication administration time

Radio Buttons

Allows a single choice.

Example:

Sex:

• Male
• Female

Checkboxes

Allows multiple selections.

Example:

Symptoms:

• Fever
• Cough
• Vomiting

Dropdown

Provides compact selection lists.

Calculated Fields

Automatically compute values.

Example:

BMI

Weight / Height²