To define permissible randomizations, a single-case design team lists every phase start or condition sequence allowed before treatment assignment. Each retained arrangement must satisfy the design's clinical and logistical constraints and have a documented selection probability. Freeze the set, exclusions, randomization method, seed or draw evidence, and analysis plan before outcomes are visible. The later randomization test must use this same assignment mechanism.

Start with the design and care constraints

Specify the design, total observations, minimum phase lengths, washout or carryover rules, treatment availability, safety gates, and any dates that cannot be assigned.

Enumerate rather than describe vaguely

Give every permissible schedule a stable ID. A phrase such as phase change sometime next week is insufficient because the assignment denominator cannot be reconstructed.

Record assignment probabilities

Equal probabilities are common but are not automatic. If blocked or weighted selection is planned, document each probability and use an analysis that respects it.

Freeze the set before the draw

Store the dated protocol, list, code, seed or physical draw record, and approval. Restrict later edits to versioned amendments that preserve the original.

Route deviations through a human gate

When a schedule changes for the person's welfare or another legitimate reason, record the event and seek qualified design advice. Do not fabricate compliance with the original scheme.

Build Dario's assignment-set register

Start with a versioned record for Dario's prospective phase-start constraints. For the define permissible randomizations single-case design question, record the protocol date, design, randomization unit, complete permissible assignment set, assignment probabilities, actual draw, test statistic, direction, tail, tie rule, missing-data rule, analysis mode, software, and reviewer. Keep Dario's raw time series in chronological order and link every derived value to its source. The packet should let an independent analyst reproduce both the observed statistic and its reference distribution.

Work the example for Dario

Dario's 12-observation phase design requires at least four baseline observations and four intervention observations. Phase starts at observations 5, 6, 7, 8, or 9 therefore form five permissible schedules. The protocol gives each a 1/5 chance and records the random selection of observation 7 before the first baseline point is collected. Preserve every intermediate assignment count, statistic, fraction, and rounding step. The example is fictional and teaches the stated method; it does not create a universal alpha, minimum design, treatment recommendation, or effect category for Dario's home morning routine study.

Audit Dario's randomization evidence

Dario's register shows all 12 time positions, the minimum-phase constraints, five included starts, excluded starts and reasons, equal probabilities, random-number procedure, selected start, timestamp, and authorized protocol version. No start is added or removed after Dario's outcomes appear. The audit also checks protocol amendments, assignment deviations, duplicate or missing observations, phase-label changes, output precision, code and package versions, and whether the reported test matches the actual randomization. Unresolved discrepancies remain on hold with an owner and due date.

Prevent the main inference error in Dario's review

A team may declare a wide set, then quietly remove inconvenient schedules after seeing the graph. That changes the reference distribution and can change the p value. Dario's immutable register and protocol hash make the prospective boundary visible. A randomization p value depends on the assignment mechanism and predeclared statistic. It does not turn nonrandom treatment changes into randomized experiments, quantify the effect's size, establish clinical importance, or estimate a population effect.

Integrate design evidence for Dario

If health, assent, safety, or access needs require departure from the selected schedule, the responsible team prioritizes the person and documents the deviation. The original randomization claim and planned test then receive a methods review; safety is never delayed to preserve an analysis. The WWC Version 5.0 handbook is a research-review standard rather than a universal care protocol. The responsible team still evaluates the design's prediction, verification, replication, phase patterns, attrition, assignment fidelity, measurement quality, and fit to the question.

Protect participation and access for Dario

Research design never outranks Dario's welfare. Keep augmentative and alternative communication, interpreters, mobility, food, water, bathroom use, prescribed care, health support, rest, relationships, and emergency help available. Use accessible communication for consent and assent processes, withdrawal, discomfort, and feedback. If the selected schedule becomes unwanted, unsafe, medically inappropriate, or infeasible, qualified people act for safety and document the design consequence.

Use randomized single-case sources within scope for Dario

For Dario's permissible randomization set, the BACB ethics hub and CASP public summary provide professional context, and the BCBA Test Content Outline identifies examination content on measurement and single-case design. A randomized SCED methods paper explains prospective assignment sets, randomization tests, and attainable p-value limits. An effect-measure paper describes a priori statistic choice and the boundary between tentative causal inference and effect magnitude. Research on rapidly alternating designs, changing-criterion designs, and randomized case series shows that assignment schemes and test behavior are design-specific. ASHA supports continuous AAC access.

Rehearse Dario's analysis before outcomes exist

Before the home morning-routine study begins, Dario's team runs the assignment-set register with a small fictional sequence. The dry run confirms that the assignment generator returns exactly the permitted schedules, the selected schedule can be traced to the random draw, and the permissible randomization set statistic matches a hand calculation. Reviewers deliberately include a tie, a missing observation, and an assignment at each boundary so default behavior becomes visible. They save the test inputs, expected outputs, code version, and correction log. This rehearsal checks the machinery for prospective phase-start constraints; it never uses Dario's future outcomes or changes the predeclared analysis after data collection.

Define Permissible Randomizations Single-Case Design Review

Review the assignment-set register with Dario, the responsible clinician, and a statistician or methodologist experienced in randomization inference. Preserve protocol, assignments, raw observations, graph, code, outputs, deviations, inference limits, client input, decisions, and future design changes. Keep the page draft and noindex until the named external reviews confirm that the research description, accessible participation, and clinical boundary are accurate.

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