To use WCF as WCF Rest service you have to enable webHttpBindings. It support HTTP GET and POST verbs by [WebGet] and [WebInvoke] attributes respectively. To enable other HTTP verbs you have to do some configuration in IIS to accept request of that particular verb on .svc files.
Concurrent validity is a measure of how well a particular test correlates with a previously validated measure. It is commonly used in social science, psychology and education. Don't miss these related articles:
In research, internal validity is when a researcher can say that only the independent variable caused changes in the dependent variable. For example, in Josh's study, the videos are the independent variables and the women's reactions are the dependent variables.