In single-subject research, a key external validity concern is whether a treatment shown to reduce self-injurious behavior in a small number of children with intellectual disabilities can be expected to work for other children with similar conditions in the broader population.

A researcher conducts a single-subject study and finds that a behavioral intervention successfully reduces self-injurious behavior in three children with intellectual disabilities. A colleague asks, 'Can we expect this treatment to work for other children with similar disabilities who were not part of the study?' Which of the following best explains why this question is difficult to answer based on the study alone?

A clinical psychologist is testing a new 'Functional Communication' intervention to reduce self-biting in children with intellectual disabilities. Match each research outcome to the conclusion it supports regarding whether the treatment will work for the broader population.

A researcher has successfully reduced self-injury in two children with intellectual disabilities using a specific behavioral protocol. Arrange the following research steps in the logical order required to systematically analyze whether this treatment will effectively generalize to the broader population.

A clinical researcher has successfully used a functional communication training (FCT) intervention to reduce self-injurious behavior in two children with Down Syndrome. Match each potential follow-up research step to the specific aspect of generalization it evaluates.

In a single-subject study where a treatment successfully reduces self-injury in two children, what is the primary concern regarding the study's external validity?

In single-subject research, if a treatment is shown to successfully reduce self-injurious behavior in a small number of participants, it can be definitively concluded that the same treatment will be equally effective for all other individuals with similar conditions in the general population.

A clinical researcher has successfully reduced self-injurious behavior in two children with intellectual disabilities using a new behavioral intervention. To analyze whether these results can be generalized to the broader population, arrange the following steps in the correct logical sequence.

A clinician reviews a single-subject study where a behavioral treatment reduced self-injury in two children ($n = 2$) and immediately decides to apply it to all clients in their facility. When evaluating the clinician's decision according to scientific standards, a critic would judge the implementation as 'premature' because the original study fails to establish sufficient _____ to justify population-wide application.

A school administrator decides to adopt a specific self-injury intervention for an entire district after reviewing a study where it worked for three children in a single-subject design. A researcher critiquing this decision would argue that the administrator is ignoring the study's lack of _____, as findings from a few individuals cannot be automatically assumed to represent the broader population.

What is the primary external validity concern raised in single-subject research when a treatment successfully reduces self-injurious behavior in a small group of participants?

Explain the research methodology concern raised by the colleague in this case. In your explanation, specify the type of validity in question and why the study's design makes generalization uncertain.

Suppose you are planning a follow-up study to address the external validity limitations of a single-subject research design that successfully reduced self-injury in two children ($n = 2$) with intellectual disabilities. What design step should you take to evaluate whether the treatment generalizes to the broader population?