Answer to Question 1
Interrater reliability would two or more clinicians diagnosis the same child with autism?
Cross-time reliability would the same clinician diagnosis the same child with autism at different ages?
Internal validity does the diagnosis of autism accurately represent the pattern of behaviors seen in children with autism?
External validity does the diagnosis mean something useful (e.g., how to treat)?
Answer to Question 2
A family systems theorist will see the individual's behavior as stemming from a family context. This person's problems will be seen as being affected by the family and, in turn, affecting other family members. The individual's behavior may be a symptom of unhealthy family dynamics. Three approaches to family therapy might be taken: communications, strategic, and structural. The communications approach to treatment would look at how the client and family convey messages. The strategic approach would emphasize power relationships among family members. The structural approach would investigate the degree to which there are over- or under-involved relationships among family members.
The multicultural theorist would emphasize the cultural norms of the client's background. For example, if the family is Asian, the degree of collectivity versus independence would be highlighted. It would be important to accept the legitimacy of the client's culture and examine whether discrimination by the majority culture contributes to the individual's distress.
Both models would focus more on the individual's larger context (family or society) than would other models. The problems of the individual would be reevaluated as problems that occur in larger groups.