Internal vs. External Validity

What is internal validity?

Extent to which the experiment shows the changes in the behavior are due to the independent variable and not the result of uncontrolled or confounding variables 

Examples of confounding variables:  

-Starting medication

-Change in home life (divorce, death, new baby, move, etc)

-Change in school/therapy life (new therapists, clinicians, new building, new school, etc.)

What is external validity?

The degree to which a study's findings have generality to other subjects, settings, and/or behaviors

-Will this study prove effective if a different population of participants is used?

-Will this study be effective if used with a different type of behaviors?

If the study was done in a clinic, will it be effective if conducted in a school classroom setting?  What about in a home environment?

Resources:  Cooper J.O, Heron T.E, Heward W.L. Applied behavior analysis (2nd ed.) Upper Saddle River, NJ: Pearson; 2007.

Test Tuesday

Which of the following is not an ethical professional claim that a BCBA or BCaBA should make:

1.  I have had success working with children like your daughter.

2.  I have experience working with children like your daughter.

3.  I am certain that I am able to help your daughter.

4.  Give me 6 months and your daughter will be a new child.  

I tricked ya!  There are two answers.  You should never say both of the following:

3.  I am certain that I am able to help your daughter.

4.  Give me 6 months and your daughter will be a new child.  

You want to make sure that you do not make professional claims such as those above due to the BACB ethical guidelines.  Review the guidelines at the following link.

http://www.bacb.com/index.php?page=100165#guidelines

Test Tuesday

Given the following example, could you use a reversal design?

  During baseline a client cannot do a single math problem.  You are wanting to put in an intervention to increase the number of addition problems a client can do.  Could a reversal design be used in this situation?  Why or why not?

No.  A reversal design can NOT be used if the behavior is learned and irreversible. 

Need a recap on the reversal design.  Check out this link.  

http://bcbatestprep.blogspot.com/2014/03/reversal-design.html

Reversal Design

Fourth Edition Task List

Section 1

B-04

Reversal Design

(Also known as ABA design)

How does it demonstrate experimental control?

Demonstrates experimental control by repeatedly introducing and withdrawing the experimental control.

Also, confounding variables are unlikely to repeatedly occur at the same times as the experimental variable

The following visual represents a typical ABA or Reversal Design. 

A= Baseline

B=Intervention

A= Baseline

So, the reversal design sounds fantastic.  What is the catch?

You cannot use the reversal design with variables that are irreversible or it is unethical to return to baseline.

Examples of when reversal designs would NOT work...

If you teach a child how to read words, it is irreversible, so a reversal design would not work.

If during baseline, the student knew how to read 3 words.  Then you implement the intervention and now the student can read 12 words.  You cannot reverse back to baseline because even if you remove the intervention the student has been taught to read 12 words and they will continue to read 12 words. It is irreversible.

If a child is engaging in head-banging during baseline 30 times per minute.  A doctor has determined that they are very close to going blind in one eye due to the intensity of the head-bangs. Therefore, if during the intervention you reduce the head-banging to 1x per hour, it would be unethical to remove the intervention and allow the child to head-bang up to 30x per minute.  In this situation, a reversal design would not work. 

Resources:  Cooper J.O, Heron T.E, Heward W.L. Applied behavior analysis (2nd ed.) Upper Saddle River, NJ: Pearson; 2007.

Continuous Measurement Procedures

Fourth Edition Task List

Section 1

A-12

Continuous measurement is conducted in a way in which ALL instances of a response class are detected during an observation period.

The following chart shows the advantages and disadvantages of the different types of continuous measurement.

Questions?  Just leave a comment, and I will get back to you! :)

Resources:  Cooper J.O, Heron T.E, Heward W.L. Applied behavior analysis (2nd ed.) Upper Saddle River, NJ: Pearson; 2007.

Basic vs. Applied Research

Basic vs. Applied Research

Basic: does not focus on real-world application, and instead it just tries to describe the fundamentals of behavior.

Applied: focuses on application in the real world, but it still is based upon previous theory and assumptions that are made. 

Try it.

In the field of ABA, are we more concerned with applied or basic research?

Applied.

Resources:  Cooper J.O, Heron T.E, Heward W.L. Applied behavior analysis (2nd ed.) Upper Saddle River, NJ: Pearson; 2007.