Step 4 · Schema

The schema step arranges your arms and phases into the randomisation sequences participants follow. It is shown as a grid: one column per phase across the trial timeline, one row per sequence.

Phases across the top

Add the phases that make up the trial in order, for example a baseline, one or more intervention periods, washouts between them, and the post-trial debrief. Baseline and debrief are single, fixed phases; intervention and washout phases can repeat.

Sequences down the side

Each sequence is one ordering of arms:

• In a parallel trial you typically have one sequence per active/sham arm, each participant follows one arm throughout.

• In a crossover trial each sequence is a different order of the same arms, every participant passes through all of them, but in a randomised order.

For each intervention cell you pick which arm fills it; for each washout cell you pick which washout arm (nothing or unmodulated) applies.

How participants are placed

When a participant enrols, the portal assigns them to a sequence at random, weighted by the completion targets you set in Step 3 · Treatment Phases. The washout assignments in this grid then determine, for each rest period, whether that participant listens to an unmodulated sound or does not listen at all.

Note

Weighted randomisation is defined per arm. In a parallel design each sequence is a single arm, so the weighting is exact. Crossover designs are supported, but the per-arm shares apply across the orderings; see Enrolment and randomisation for the detail.

Next: Step 5 · Sessions.