One of the biggest mistakes, that is a huge
problem, is misunderstanding that a case study is not a single-subject experimental design.
There are controls that need to be implemented, and a case study does not equate to a single-subject
experimental design. People misunderstand or they misinterpret
the term “multiple baseline” to mean that because you are measuring multiple things,
that that gives you the experimental control. You have to be demonstrating, instead, that
you’ve measured multiple behaviors and that you’ve replicated your treatment effect across
those multiple behaviors. So, one instance of one treatment being implemented with one
behavior is not sufficient, even if you’ve measured other things. That’s a very common
mistake that I see. There’s a design — an ABA design — that’s
a very strong experimental design where you measure the behavior, you implement treatment,
and you then to get experimental control need to see that treatment go back down to baseline,
for you to have evidence of experimental control. It’s a hard behavior to implement in our field
because we want our behaviors to stay up! We don’t want to see them return back to baseline. Oftentimes people will say they did an ABA.
But really, in effect, all they did was an AB. They measured, they implemented treatment,
and the behavior changed because the treatment was successful. That does not give you experimental
control. They think they did an experimentally sound design, but because the behavior didn’t
do what the design requires to get experimental control, they really don’t have experimental
control with their design.