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Trial-by-Trial & Probe Data: 2 Essential Ways to Efficiently Collect Data for IEP Goals


In the field of Applied Behavior Analysis (ABA), two common methods of data collection are probe data and trial-by-trial data. In any special education classroom, data collection is an essential aspect of designing and assessing Individualized Education Program (IEP) goals for students with autism or other disabilities. Accurate and reliable data collection helps educators make informed decisions, monitor progress, and tailor instructional strategies to meet the unique needs of each student. In this blog post, we’ll explore when to probe data or trial-by-trial based on the specific skill being targeted.

Probe Data: An Overview

Probe data collection involves collecting one data point on the FIRST trial of a program. After that, staff are still practicing and teaching the skill, but not collecting any data for the remainder of that instructional session.

IEP criteria for a skill using probe data collection might read “completes this skill successfully on four out of five consecutive opportunities.”

Check out these FREE probe data sheets.

probe data sheet Trial-by-Trial & Probe Data: 2 Essential Ways to Efficiently Collect Data for IEP Goals

When to Use Probe Data

Probe data is often collected during the initial stages of teaching a skill to establish a baseline. A baseline data point helps determine the starting point for instruction and provides a benchmark against which progress can be measured.

During skill acquisition, probe data is an ideal data collection tool for skills that are only practiced once per day, or several times per week, since there is only one trial being conducted during any given instructional session. Examples could include: retrieving lunchbox for snack, putting on coat for recess, or stopping at the curb during a community outing.

Probe data can be beneficial for students who only need a couple of exposures to new skills to absorb new information, and can meet the mastery criteria within session to move on to additional targets or skills.

While probe data is useful for skills that are not practiced frequently, it can still be utilized for skills that are practiced more often. In fact can be seen as a time saver in that staff need to record fewer data points, and can spend more time actually teaching the skill during a session. There is research to show that using this type of discontinuous data collection tool can help students reach mastery criteria sooner than when using trial-by-trial (continuous) data collection criteria.

Trial-by-Trial Data: An Overview

trial by trial data Trial-by-Trial & Probe Data: 2 Essential Ways to Efficiently Collect Data for IEP Goals

Trial-by-trial is a continuous data collection method that records the student’s response on each individual trial or teaching opportunity. Once all trials are completed, a percentage score is calculated (e.g., 8 out of 10 trials correct = 80% success). This method provides detailed information about the student’s progress and allows for more precise analysis of instructional strategies.

Browse FREE trial-by-trial data sheets.

Trial-by-trial data helps educators identify patterns, trends, and specific areas of difficulty. It is particularly useful when working with learners who are slower to progress through learning new skills and/ or need prompts embedded into their learning trials. (These prompts may be faded out systematically over time according to their performance). Trial-by-trial data is more sensitive in that it captures the learner’s entire performance during an instructional session, rather than just one initial data point.

There is research to suggest that using trial-by-trial data promotes a higher rate of maintenance in skill acquisition. However, a downside to this method is that of course it can be time consuming to record data on each and every trial conducted within an instructional session.

Trial-by-trial data is also valuable when targeting skills that require generalization across different settings, materials, or individuals. It allows educators to track the student’s performance across various contexts and identify any inconsistencies or difficulties in transferring skills.

Another benefit of trial-by-trial data is that you can easily graph your data by inputting the daily percentage scores over time. The graph provides you with an instant visual of student progress so that you can monitor your teaching strategies accordingly!

Click here to check out a digital data tracker.

data tracker Trial-by-Trial & Probe Data: 2 Essential Ways to Efficiently Collect Data for IEP Goals


Data collection plays a crucial role in guiding instruction, monitoring progress, and evaluating the effectiveness of interventions for students with autism or special needs. The choice between probe data and trial-by-trial data depends on the specific skill being targeted, as well as the resources and staff within your classroom! Probe data provides a broad overview of a student’s skill level and is ideal for establishing a baseline performance, tracking skills that are practiced infrequently, or with learners who absorb new skills quickly. It can be a quick and efficient means of data collection in a busy classroom. On the other hand, trial-by-trial data allows for a deeper analysis, making it suitable for learners who practice skills repeatedly during session, are more inconsistent or slow in their rate of progress, or when assessing skill generalization. By understanding the strengths and limitations of each data collection method, you can make informed decisions to choose which data collection system is best for you and the unique needs of your classroom!


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