To aggregate ABA data across sessions without weighting errors, decide whether each session or each opportunity should carry equal influence. A mean of session percentages weights sessions equally. A pooled percentage weights eligible opportunities equally. Show both formula and raw counts, and keep incompatible conditions separate. The preferred aggregation follows the decision, not whichever result looks stronger.

Choose the unit that receives weight

Use equal session weight when each session is the intended unit. Use opportunity weight when compatible opportunities are the intended unit.

Keep raw session rows

Preserve each numerator, denominator, condition, date, and support so reviewers can reconstruct any aggregate.

Avoid pooling unlike conditions

Separate baseline, teaching, probes, settings, partners, definitions, and procedure versions before aggregation.

Name the decision effect

If aggregation methods lead to different actions, explain why and review exposure structure rather than selecting the preferred result silently.

Decide what equal influence means

An unweighted mean gives every included session the same influence even when one session contains two opportunities and another contains ten. That can fit a question about the average session, provided the sessions are eligible and comparable. A pooled percentage gives every eligible opportunity the same influence. That can fit a question about performance across the combined opportunity set, provided the opportunity definition and conditions are compatible.

Neither method repairs incompatible data. If one session used a new response definition, removed AAC access, applied different prompting, or sampled a different setting, preserve it as a separate condition. Document the aggregation choice before reviewing which result is more favorable.

Use the formula and its units for Eli

For Eli's cross-session aggregation worksheet: unweighted session mean = sum of session percentages / sessions; pooled percentage = total responses / total eligible opportunities × 100. Write the unit beside every result and keep the original numerator, denominator, time, opportunities, response definition, and condition. State rounding only after the unrounded calculation is preserved.

Work the arithmetic for Eli

Eli responds in 1 of 2 opportunities, or 50%, then 9 of 10, or 90%. The unweighted mean is (50% + 90%)/2 = 70%. In that calculation, each session supplies half the result.

For the pooled calculation, the success numerator is 1 + 9 = 10 and the opportunity denominator is 2 + 10 = 12. The pooled result is 10/12 = 83.33%, reported as 83.3% after rounding. The first session supplies 2/12, or 16.7%, of the pooled opportunity weight, while the second supplies 10/12, or 83.3%. The difference between 70% and 83.3% comes from the weighting unit. Neither result is an arithmetic error.

Handle zero and missing denominators

A session with zero eligible opportunities has no session percentage and cannot enter the unweighted mean as 0%. It contributes zero opportunities to a pooled denominator, but the no-opportunity state remains visible because it may reveal an access or scheduling problem. A missing session is also retained as missing rather than converted to zero or silently dropped. Report the number of valid included sessions beside an unweighted mean and the total numerator and denominator beside a pooled percentage.

Report the aggregation without hiding the choice

A clear note could read: "Across two compatible sessions, Eli responded in 10 of 12 eligible opportunities, or 83.3%. The mean of the two session percentages was 70% because each session received equal weight. The pooled result was selected for the combined-opportunity question; both session rows remain visible." A graph should still show the original 50% and 90% session values and denominators. The aggregate is a summary, not a substitute for the series.

Apply the aggregation method to a clinical decision

Eli's qualified clinician identifies the decision before selecting the summary or display. Compare at least one alternative unit or classification, inspect client access and direct experience, and record what evidence would change the interpretation. A correct calculation can still answer the wrong question.

Audit data states for Eli

Eli's record distinguishes valid observed values, true zeros, missing observations, invalid events, no opportunities, not-due records, late entries, corrections, and incompatible conditions. Give unresolved items an owner, age, and next action. Preserve the original evidence and the reason for every exclusion or change.

Protect access and context for Eli

Eli's measurement keeps AAC, interpreters, mobility, food, water, bathroom use, prescribed care, health support, rest, relationships, and emergency help available. Record ordinary supports, partner response, setting, schedule, burden, and withdrawal. The data system should describe care without creating unsafe or inaccessible test conditions.

Ask five calculation questions for Eli

Use these questions in the cross-session aggregation worksheet:

  • What exact response, event, opportunity, time exposure, unit, and condition does the value represent?
  • Which raw numerator, denominator, clock, source, and calculation reproduce it?
  • Which zero, missing, invalid, not-due, corrected, censored, or incompatible states stay separate?
  • Which client experience, access, integrity, agreement, burden, and context qualify interpretation?
  • Which clinical decision, alternative display, next evidence, owner, and review date follow?

Keep raw counts and units beside every derived value.

Use current sources within their scope for Eli

For Eli's cross-session aggregation worksheet, the BCBA Test Content Outline includes measurement, validity, reliability, sampling, graphing, assessment, and data-based decisions as examination content. It is not a case protocol. The BACB Ethics Code addresses competence, client involvement, consent and assent when applicable, documentation, risk, and evaluation for covered behavior analysts. The CASP public summary supplies high-level autism-treatment scope without publishing licensed detailed procedures.

For Eli, ASHA says AAC users should always have access to their communication tools or devices. The WWC Version 5.0 handbook supplies research-review standards, not universal clinical formulas, thresholds, or decision rules. None of these sources turns a derived metric into proof of effectiveness, safety, medical necessity, compliance, or causation.

Close Eli's measurement review

Ask Eli and the responsible clinician to review the cross-session aggregation worksheet through accessible communication. Record the raw data, calculation, unit, display, assumptions, missingness, context, interpretation limits, selected decision, next evidence, and review date. Reopen the analysis when the response definition, exposure, opportunity, setting, measurement system, client priority, or access changes.

Related resources

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