A good data definition provides ALL the characteristics of forms (questionnaires, CRFs) and the associated variables. What is needed is good old "TLV".
| Stands For.. | Overview | |
|---|---|---|
T | Type of Variable | The most common types are dates, number, coded variables (e.g., 0 = No, 1 = Yes;). |
L | Layout and Logic | Indicate the look and feel of the variable, and when it should be displayed (e.g., only show if subject is a male). |
V | Validation | Indicate the rules that govern the acceptable variable values (acceptable range, units) |
What To Do
Use A Spreadsheet
Document your data definition using the spreadsheet sent by Studytrax. Learn how to complete the spreadsheet here.
Leverage Standards
Learn About Data Definition Standards (see here)
Determine Forms
For non-standardized forms (e.g., SF-36), the main factors that determine what variables to put on a form are:
- Time and Collection Methods (see image)
- What variables are collected together at specific time points?
- Note: Forms can be shared across studies (e.g., Demographics, Contact Information)
- Are all the variables on a forms ALWAYS collected together? If not, often best to separate time-related groups of variables (e.g., rare vs. common lab values)
- What variables are collected together at specific time points?
- Domain - What variables belong to a given content domain (e.g., surgical vs. imaging variables)?
- Practical -
- Create Once - Forms are created ONCE and then used at one or more study visits.
- Pre-Defined Fields - Exclude any fields that are pre-defined in Studytrax:
- Reference ID
- Global ID (e.g., SSN, MRN, bogus auto-generated)
- Project ID
- Study specific (i.e., screening ID)
- Randomization ID
- Name (i.e., First, Last, Middle Initial)
- Site
- Reference ID
Mark It UP
The best preparation for completing the data definition spreadsheet is to mark all forms with the data definition characteristics.
Example Marked Up Form
Keep It Simple
Forms should use the cleanest, simplest layout possible. Standard practice is to use one-row-per-variable (examples here).
Leverage Visual Validation
A form's spatial and visual layout can be it's most important validation (see examples here).
Indicate Timing
Document which forms are collected with each study event by completing the Data Collection Schedule tab on the "NewStudyStartup" spreadsheet (provided by Studytrax staff).