Problem: Find and read a published case study in psychology. (Use case study as a key term in a PsycINFO search.) Then do the following: Describe one problem related to internal validity. Describe one problem related to external validity. Generate two testable hypotheses suggested by the case study that might be interesting to test in subsequent studies. One of the studies should be experimental in nature and one should be non-experimental. Briefly summarize the key manipulations, variables, or observations that you would include in each study. related toInternal and external validity of Attention-Deficit Hyperactivity Disorder in a population-based sample of adults. Need Assignment Help?