A one group design is a form of research that is used to determine if the treatment or intervention on a person or group of people has been effective in the person or group of people changing the way that one was behaving. When this form is used a person or group of people will be placed into a group and will be provided with the same treatment for a condition and the same assessment will be used. The second feature to this research method will require that an assessment of the variable will be looked at before and after treatment.
When an outcome evaluation program is looked at it will be looked at to see if the same treatment works for everyone that was provided that treatment, in most cases this will not work. When a juvenile offender is adjudicated of a crime, he or she may be expected to complete a program where he or she may pay his or her debt to society by completing community service projects. Once the juvenile completes the sentence that the Judge gave him or her the juvenile may be looked at to determine if he or she has changed his or her behaviors by completing this program. The juvenile may be looked at to see if he or she has learned to change his or her behavior, as well as, the way he or she thinks or reacts to a situation. These methods were looked at to determine if people who completed these programs developed new attitudes or mindsets and it will also help to determine if this form of discipline is working.
In your example, what might be some threats to the internal validity?