The following web page is designed to provide an introduction to internal validity and to familiarize you with the potential threats or obstacles to achieving internal validity. To begin, we should have a clear idea what validity means. Validity is the best available approximation to the truth of a given proposition, inference or conclusion. In other words, when we make some claim, does the evidence support our conclusions. Validity is divided into four categories.
Internal validity focuses on cause and effect relationships.
The notion of one thing leading to another is applicable here. For example, it is believed that listening to Selena twice a day causes adolescent girls to crave fajitas and develop an uncontrollable urge to attack pinatas. However, if we want to test such a claim for internal validity, then we must be able to measure this unusual phenomenon for causality. As we stated earlier, causality is critical to internal validity. Now, let's see how we might be able to help our Selena fans.