Surveys sometime contain "loops," sub-sections of the survey that are repeated several times. This is common in product concept testing and patient case reviews:
What are survey data loops?
Loops are a sequence of repeated instructions. For example, a survey might ask a physician to answer questions for three patient cases. The survey asks questions for patient case 1, then repeats the same questions for patient case 2, etc.
Flatten vs stack
Survey data loops can be represented as flatted data or stacked data. Protobi can represent both structures.
Flattened data has one row per respondent, and one column per question per loop:
Stacked data has one column per question and one row per respondent per loop:
Clients often ask us to stack data with flattened patient cases. Stacking can be done programmatically in the tool. Survey loops are appended vertically--similar to stacked waves of data. Data for each patient case (B1.1, B1.2, etc.) is put in a single stacked data column (B1).
Below is a PDF with a more detailed discussion...