Planned activity check

PLACHECK samples a group at planned instants

An ABAI educational article describes PLACHECK as a group time-sampling procedure. At a timer signal, the observer scans the group and counts how many participants are engaged under the operational definition.

Activity before or after the check does not change that score. The procedure therefore estimates the state of the group at sampled moments. It does not produce the exact duration or number of responses for each person.

Define the activity and eligible group

Write observable inclusion and exclusion examples. “Participating appropriately” leaves too much judgment. A clearer definition might include handling assigned materials, communicating about the current task, watching the demonstrated step, or using an agreed break routine.

Define who enters the denominator at each checkpoint. A person who is absent, receiving health care, or outside the activity under the planned schedule may be ineligible. A participant whose required communication device or materials are missing could remain eligible while the environmental failure is recorded, depending on the question. Decide before observation.

Build the checkpoint schedule in advance

Specify the session start and end, timer, checkpoint spacing, scan order, scoring window, missed-check rule, and tolerance for a delayed scan. Moving a check to a quieter moment changes the sample.

Long intervals reduce observer workload and can miss brief changes. Very short intervals may repeatedly sample the same episode and burden the observer. Match spacing to expected activity patterns and the decision being made. Mark a new version when timing changes.

Calculate participant-checks carefully

At one checkpoint, six of eight eligible participants may be engaged. That checkpoint equals 75%. Across a session, a stronger denominator is often the sum of engaged participant-checks divided by all eligible participant-checks.

This approach handles changing attendance. Averaging checkpoint percentages can give equal weight to a check with two participants and one with ten. If the goal is to give each checkpoint equal weight, state that method instead. Preserve raw counts so readers can see the difference.

A fictional after-school group

An after-school activity schedules ten checkpoints for a group of up to eight participants. Attendance and eligibility vary, producing 74 eligible participant-checks. Observers score 61 engaged participant-checks. Group sampled engagement is 61 of 74, or 82.4%.

Two additional scheduled checks are missed during a building alarm and remain missing. Check completion is 10 of 12, or 83.3%. The missed checks never become zero engagement.

The observer also records six chosen-break participant-checks, four material-unavailable checks, and three other states. Those categories explain the denominator without assigning every nonengaged score to the participant. Counts can overlap only when the protocol explicitly permits it.

Group averages can hide individual experience

A high group percentage may coexist with one participant having no accessible materials. A low group result can reflect a delayed activity start, confusing instruction, noise, or unavailable staff support. Review environmental measures and individual data when decisions affect a particular person.

PLACHECK should not rank participants or turn support needs into compliance scores. Keep speech, AAC, gesture, movement, and other effective participation forms in the definition. A chosen break may be a successful response when that is part of the agreed activity plan.

Compare PLACHECK with other procedures

Momentary time sampling often measures whether one person's response occurs at the check. PLACHECK extends the momentary scan across a group. Partial-interval recording scores any occurrence within an interval, while whole-interval recording requires occurrence across the interval.

Radley and colleagues compared classroom observation methods using simulated data and reported favorable PLACHECK accuracy in those simulations. The study does not establish one best method for every group, response, interval, or clinical decision.

Train observers and review sampling quality

Practice the scan order so one participant is not consistently observed later than another. Calibrate with examples and close nonexamples. Sample agreement across activities, group sizes, times, and response states.

Report planned, valid, missed, and excluded checkpoints. Include numerator, denominator, group size, setting, activity, observation window, and version. Agreement supports scoring consistency while representativeness still depends on the sampling frame.

Review results by activity and time when the sampling plan supports that split. A single overall percentage can hide a reliable material delay at the start of every session or a consistent access barrier during one group routine.

The BACB BCBA Test Content Outline, Sixth Edition covers time sampling, reliability, validity, and selecting representative procedures. It supplies exam content rather than a mandated PLACHECK schedule.