Concurrent versus nonconcurrent multiple-baseline evidence differs in how tiers share calendar time. Concurrent tiers are observed during overlapping periods, which can help reveal common historical events. Nonconcurrent tiers may begin in different periods and still provide staggered replications, while requiring stronger timing, assignment, baseline-length, and history documentation. Review the delivered design and current standard rather than treating the labels as interchangeable.

Plot actual calendar time

Store dates and observation numbers so reviewers can see whether tiers were active during the same external events.

Document start assignment

Record fixed, randomized, or response-guided baseline lengths and preserve the planned and delivered starts.

Assess historical threats

List program, staffing, policy, seasonal, environmental, and measurement changes that could align with outcomes.

Review baseline overlap and staggering

Show how much tier baselines overlap and whether phase changes occur at sufficiently distinct times for the design question.

Apply the relevant standard

State how the current review framework evaluates concurrent and nonconcurrent variants and where methods debate remains.

Build Pia's concurrency comparison file

For the concurrent versus nonconcurrent multiple baseline evidence question, create a versioned concurrency comparison file. Preserve the target definition, unit, opportunity or observation time, raw series, graph, phase boundaries, design logic, predicted changes, planned demonstrations, actual implementation, measurement quality, client input, access and safety evidence, context, reviewer judgments, and claim status. The record should let another qualified reviewer reconstruct Pia's evidence without relying on a summary score.

Work through Pia's replication example

Pia's concurrent version observes all three sites during March and introduces the condition on March 8, 15, and 22. Its nonconcurrent version enrolls one site in March, one in May, and one in August with fixed baseline lengths. Both stagger starts, but only the concurrent version shows untreated tiers during each earlier site's change on the same calendar dates. Display every value, phase, denominator, and time sequence. This fictional regional three-site communication study example illustrates one evidence pattern and does not establish a universal phase length, effect threshold, functional relation, treatment recommendation, or review outcome.

Audit Pia's design evidence

Pia's file stores enrollment, every observation date, baseline length, start assignment, site context, shared events, implementation, and graph. It identifies which tiers overlap in calendar time and never infers concurrency from aligned observation numbers alone. The audit also checks graph axes, session spacing, invalid and missing states, implementation fidelity, condition discriminability, carryover, definition changes, concurrent events, software settings, and correction history. A missing field does not become a negative value or disappear from the denominator.

Address Pia's main inference risk

Nonconcurrent does not mean invalid, and concurrent does not guarantee control. Poor staggering, response-guided selection, shared measurement errors, or simultaneous disruptions can weaken either format. Pia's review applies design-specific evidence and limits. Reviewers describe the raw pattern first, then the narrower conclusion it supports. A clinical improvement can be real and valuable even when the design cannot attribute it confidently, and a strong experimental contrast can still lack personal importance.

Decide the next evidence step for Pia

The report explains why the selected format fit recruitment and care, how historical threats were assessed, and whether each tier produced a temporally related replication. Current WWC treatment and methodological literature are cited separately. The responsible clinician and methodologist choose any added observation, replication, design change, or claim revision. The choice protects needed care, uses prospectively stated rules where possible, and preserves the original graph and decision history.

Protect Pia's access and participation

Keep Pia's augmentative and alternative communication, interpreters, mobility, food, water, bathroom use, prescribed care, health support, rest, relationships, and emergency help available throughout the regional three-site communication study. Use accessible consent and assent processes when applicable and respond to withdrawal, dissent, or distress. A replication plan never supplies authority to withhold a necessary support or delay urgent action.

Apply current sources to Pia's review

Pia's source set includes dedicated nonconcurrent multiple-baseline research so the comparison reflects more than a shared-time definition. The BACB ethics hub and CASP public summary provide professional context, while the BCBA Test Content Outline identifies examination content on measurement and single-case design. The WWC Version 5.0 handbook supplies a current research-review framework. A single-case design review, systematic visual-analysis protocols, current analytic reflections, nonconcurrent multiple-baseline methods research, and a visual-analysis software tutorial describe methods and limits. ASHA supports continuous AAC access.

Rehearse Pia's review process

Before live use, run the concurrency comparison file on fictional graphs with a strong effect, weak effect, delayed effect, opposite trend, carryover, missing agreement, one contradictory tier, and no replication. Confirm that reviewers preserve raw values, count planned opportunities separately from observed demonstrations, identify holds, and keep client relevance distinct from causal inference. Store test cases, expected decisions, software version, and correction log.

Close Pia's claim review

Review the concurrency comparison file with Pia, the responsible clinician, and a methodologist familiar with the exact design. Preserve raw data, graph, design protocol, basic effects, demonstrations, fidelity, measurement checks, contextual events, client input, reviewer disagreements, source standard, final wording, and limits. Keep the page draft and noindex until all manifest-named reviews are complete.

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