To calculate total count IOA in ABA, divide the smaller observer count by the larger observer count and multiply by 100. Verify that both observers watched the same exposure and used the same definition. Report both counts. A high result shows similar totals, while disagreements about which events occurred or when they occurred can remain hidden.

Match the observation exposure

Confirm identical start, stop, setting, client, and unavailable periods. Similar counts from different exposure are not a valid pair.

Keep both raw totals

Publish 18 and 20 beside 90%. The raw difference helps readers understand the calculation.

Inspect temporal disagreement

Compare event timestamps or interval counts when the decision depends on pattern, clustering, or specific events.

Use a stricter method when needed

Select interval, trial, or event agreement when total similarity could mask clinically important disagreement.

Verify that the two totals describe the same opportunity

Before calculating, reconcile the observation start and stop times, pauses, setting, response definition, and any periods when one observer could not see or hear the relevant event. If the observers watched different amounts of time, a count comparison confounds agreement with exposure. Preserve the mismatch as a coverage problem and do not force the records into one IOA pair.

Keep missing and invalid observations distinct from a count of zero. Zero means the observer watched the defined exposure and recorded no events. Missing means the required observation was not available. An interrupted session may still support a calculation for the exact shared portion when that rule was defined and the shared time can be reconstructed.

Read 90% as count similarity only

Iris's total-count result says the smaller total is 90% of the larger total. Across 45 minutes, the observers recorded rates of 18/45 = 0.40 and 20/45 = 0.44 events per minute after rounding. The two-event difference remains visible in either form.

Neither calculation identifies which events matched. One observer could miss two events while also recording two different events that the other observer did not record, producing equal totals with weak event correspondence. When event identity, sequence, bursts, or latency drives a decision, add timestamp matching or another method suited to that question.

Use the formula and units for Iris

For Iris's total-count IOA worksheet: total count IOA = smaller observer count / larger observer count × 100. Keep observer records independent until both are locked. Preserve the matched exposure, raw observations, numerator, denominator, unrounded calculation, and final rounding.

Work the arithmetic for Iris

Iris's observers record 18 and 20 defined events during the same 45 minutes. Total count IOA is 18 / 20 × 100 = 90%. They could still disagree on the timing or identity of individual events, so the event records and clinical question remain important.

Apply total-count agreement to the decision

Iris's qualified clinician identifies the decision before choosing an agreement method or threshold. Compare a stricter or complementary method when prevalence, totals, or aggregation could hide relevant disagreement. Repair definitions, visibility, training, sampling, or matching before judging the implementer or client data.

Audit observer and sample conditions for Iris

Iris's record identifies observers, independence, training, recording mode, shared exposure, response definition, procedure version, observation coverage, missing pairs, reactivity, and disagreements. Consent, privacy, recording, employment, supervision, and payer rules remain separate requirements. Keep every open pair visible with an owner and next action.

Protect client access during Iris's observation

Iris's observation keeps AAC, interpreters, mobility, food, water, bathroom use, prescribed care, health support, rest, relationships, and emergency help available. Do not create extra distress or remove ordinary supports to obtain an agreement sample. Record when access, health, withdrawal, or observer presence changes the condition.

Ask five IOA questions for Iris

Use these questions in the total-count IOA worksheet:

  • Did both observers independently score the same exposure, unit, definition, and condition?
  • Which calculation, numerator, denominator, prevalence, and rounding reproduce the result?
  • Which disagreements, missing pairs, invalid units, reactivity, or matching problems remain?
  • Which validity, treatment-integrity, client-outcome, experience, and access questions stay separate?
  • Which repair, complementary method, next sample, owner, and review date follow?

Keep raw observer records and disagreement types available.

Use current sources within their scope for Iris

For Iris's total-count IOA worksheet, the BACB ethics hub points to current professional ethics materials. The CASP public summary provides high-level autism-treatment scope without licensed detailed procedures. The BACB Ethics Code addresses competence, client involvement, consent and assent when applicable, documentation, risk, supervision, and evaluation for covered behavior analysts. The BCBA Test Content Outline includes measurement, reliability, sampling, and data-based decisions as examination content rather than a case protocol.

For Iris, Vollmer, Sloman, and St. Peter Pipkin discuss practical implications of data reliability and treatment-integrity monitoring. Essig, Rotta, and Poling review IOA and fidelity reporting in an identified ABA research corpus. Reed and Azulay describe a calculation tool and agreement methods. ASHA says AAC users should always have access to their tools or devices. These sources do not create one universal IOA method or threshold.

Close Iris's agreement review

Ask Iris and the responsible clinician to review the total-count IOA worksheet through accessible communication. Record the method, arithmetic, sample, disagreements, limits, measurement repair, selected decision, next observation, and review date. Reopen the analysis when the definition, observer, system, exposure, prevalence, client access, procedure, or decision changes.

Clinician release checklist

  • Do both records cover the same 45 minutes and the same valid observation conditions?
  • Are the raw totals of 18 and 20 visible beside the 90% result?
  • Are zero, missing, interrupted, and invalid observation states separated?
  • Does the clinical question require event matching, interval agreement, or another more local method?
  • Are disagreements linked to a measurement repair, owner, next sample, and review date?

Related resources

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