Parametric analysis

Parametric analysis refers to evaluation the intervention (treatment ) or independent variable in an applied behavior analysis (ABA) study or experimental design

There are two ways to describe the independent variable: parametric and nonparametric.

If an independent variable is nonparametric- it is either on or off. The easiest way to think of this is a light switch. The lights are either on or off.  If an independent variable is parametric it can have ranges or gradients of value such as a dimmer switch.  

When the independent variable is nonparametric, the goal of the experiment is to determine if an intervention is working. When an independent variable is nonparametric, the goal is to determine how much of the independent variable is most effective. 

Another everyday life example would be medication. If a person is diagnosed with strep throat they may take antibiotics for 10 days. This is a nonparametric independent variable. They are either taking the antibiotic or they are not taking the antibiotic. In contrast, if a person is on Adderall for ADHD, the doctor may test different dosages to see which is the most effective for that individual. In this case, Adderall is a parametric independent variable. 

As you can see in a real situation, this is a really easy concept to understand but applying it to clinical examples can be more confusing. Here are three examples of each:

Case Study 1

Nicholas is a four year old boy diagnosed with Autism. He presents with eloping and non compliance. He will often leave the instruction area during sessions and refuse to come back to the table after his breaks. 


The BCBA instructs his therapist to use a token board with 5 tokens and a choice board to promote compliance during the session. The BCBA wants to test how many tokens works best for Nicholas so the therapist is instructed to vary the number of tokens from 3-10 and collect data on which is most effective. The BCBA then uses this data to determine how many tokens are best for Nicholas. 


The BCBA instructs his therapist to use a token board with 5 tokens and a choice board to promote compliance during the session. Every time Nicholas gets 5 tokens he is permitted to choose an item from his choice board. The BCBA instructs the therapist to remove the intervention after three sessions occur during which eloping occurs at a rate of less than 1 time per hour.  The therapists are instructed to collect baseline line data without the intervention in order to validate whether or not the intervention works. After a stable baseline, the therapists reintroduce the intervention to replicate the treatment effects. 

This is an example of a single subject reversal ABA design using a nonparametric independent variable. 

Case Study 2

Joe is struggling with toilet training, specifically with sitting on the potty. He will frequently cry when sitting on the toilet and then stand up and go to the bathroom as soon as he gets off the toilet.


The BCBA on the case decides to introduce a parametric intervention. They decide to have Joe sit with his iPad for 5 mins on the toilet on Monday, 3 mins on Tuesday, 7 minutes on Wednesday, 10 mins on Thursday and 8 mins on Friday for two weeks to see how long is best for Joe to sit on the toilet. 


The BCBA instructs mom to have Joe sit on the toilet for 5 mins every time he tries to use the bathroom. 

Case Study 2

Jillian is very fidgeting in sessions and frequently gets off task. Her mom buys her a trampoline which she loves to use. Her therapist realizes that after jumping on the trampoline she is more on task and communicates this to the BCBA.


The BCBA implements non-contingent reinforcement (NCR) breaks for Jililan to use the trampoline during the session. The BCBA instructs the therapist to give Jillian a 5 minute trampoline break switching back and forth between every 10 mins, 20 mins and 30 mins randomly for a week to see how often Jillian needs a break. 


The BCBA implements non-contingent reinforcement (NCR) breaks for Jililan to use the trampoline during the session. The BCBA instructs the therapist to give Jillian a 5 minute break every 30 mins. 

This article is useful for registered behavior technicians (RBT) or students who are studying to become board certified behavior analysts (BCBAs). Understanding (Applied Behavior Analysis) ABA terms is critical for both being an effective ABA therapist and passing your BCBA exam


In an effort to help you study for your BCBA exam more effectively, this post is written in a “study note” form rather than as a long form blog post. 

They are my personal study notes I am sharing with you as a gift. I am spending my time studying so they are not edited. I am grateful for your understanding in overlooking the grammar! Happy Studying! 


Cooper, J. O., Heron, T. E., & Heward, W. L. (2007). Applied Behavior Analysis (3rd Edition). Hoboken, NJ: Pearson Education.

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