A whole-interval recording percentage equals valid intervals in which the defined response met the full-interval rule divided by all valid intervals observed, multiplied by 100. Define any allowed gap before collection. Report valid versus planned coverage separately. A negative interval can contain substantial responding, so the percentage is a sampled measure and does not report exact duration.

Define the full-interval rule

Specify onset, offset, allowable gap if any, interval length, and transition treatment.

Separate negative from invalid

A valid interval with an interruption can be negative; a missing observation is invalid.

Report coverage

Keep valid, planned, and excluded intervals with reasons.

Use duration when needed

Continuous timing answers exact time-occupied questions more directly.

Match the method to sustained responding

A whole-interval recording percentage asks whether the response met the rule across an entire interval. It may be useful when sustained engagement or another continuing response is the focus and continuous timing is impractical. The result does not equal exact duration. Responding that fills most of an interval can still score negative when the full-interval rule is not met.

Define whether any interruption makes an interval negative or whether a brief, specified gap is allowed. The rule should come from the measurement question and be set before observation. Changing it after seeing the data creates a different procedure and prevents a clean comparison with the earlier sample.

Design the interval record before collection

State the response definition, interval length, total observation window, clock cue, transition rule, allowed gap, and visibility standard. Use explicit marks for positive, negative, missed, invalid, and outside-exposure intervals. Record the activity and relevant setting conditions without placing unnecessary sensitive details on a broadly visible form.

Pilot the method in the actual environment. Confirm that observers can monitor the response for the entire interval while also meeting safety and access responsibilities. If competing duties repeatedly interrupt observation, redesign the sample or select a measure the team can implement accurately.

Calculate and verify the result

Count the planned intervals first. Classify missed or invalid intervals under the predeclared rules and retain their reasons. The valid denominator contains all scorable positive and negative intervals. Divide positive whole intervals by valid intervals and multiply by 100. Calculate valid divided by planned intervals as coverage.

For Grace, the result is 6 of 15 valid intervals, or 40%, with 15 of 16 planned intervals covered, or 93.8%. An independent reviewer should reproduce both results from the raw sheet. Keep the unrounded values in the calculation record and use one stated display rule.

Build the calculation around a clear decision

The whole-interval worksheet for Grace identifies the response definition, unit, interval or event boundary, planned exposure, valid denominator, missing-state rule, calculation, responsible qualified role, and review date before data collection.

Worked example: 16 planned intervals

Grace has 16 planned intervals. One is invalid after lost visibility, leaving 15 valid. Six meet the full-interval rule. Whole-interval percentage is 6 divided by 15, or 40%. Coverage is 15 divided by 16, or 93.8%. The invalid interval remains visible.

Report coverage with the result

For Grace, report planned, observed, valid, positive, negative, missed, invalid, and outside-exposure units as applicable. Preserve raw records, timestamps, interval length, procedure version, and rounding. A sampled percentage retains the limits of the selected procedure.

Keep access available during measurement

During the transparent whole-interval calculations review for Grace, keep AAC, interpreters, mobility, food, water, bathroom use, prescribed care, health support, rest, relationships, and emergency help available. Record access or health changes and use accessible communication to ask whether the outcome matters.

Use evidence within its stated scope

For Grace, the BACB ethics hub and CASP public summary provide professional context. The BCBA Test Content Outline covers continuous and discontinuous procedures, temporal dimensions, product measures, validity, reliability, and representative measurement as examination content.

For the transparent whole-interval calculations question, Pritchard and colleagues and Wirth and colleagues examine accuracy and decision implications of discontinuous measurement procedures. Lobo and colleagues supply single-case measurement and analysis context. ASHA says AAC users should always have access to their communication tools or devices. These sources support careful method selection without creating a universal interval length, correction factor, or clinical threshold.

Document the clinical review

Review the whole-interval worksheet with Grace and the responsible clinician. Record the procedure, raw data, coverage, calculation, limitations, selected action, owner, next sample, and review date. Reopen the method when the response pattern, access, setting, interval, exposure, system, or decision changes.

Clinician review checklist

  • Is the full-interval rule observable and agreed before collection?
  • Are interruptions, transitions, and any allowed gap defined?
  • Can observers distinguish valid negative intervals from missed or invalid ones?
  • Are the positive percentage and observation coverage reported separately?
  • Does the interpretation avoid treating the result as exact duration?
  • Were the same response, interval, setting, and exposure rules used across comparisons?
  • Has the person had an accessible opportunity to comment on the measured outcome?

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