Use a standard essay format for responses to all questions (i.e. an introduction, middle paragraphs and conclusion).

Responses must be submitted as a MS Word Document only, typed double-spaced, using a standard font (i.e. Times New Roman) and 12 point type size.

Word count is NOT one of the criteria that is used in assigning points to written assignments. However, students who are successful in earning the maximum number of points tend to submit written assignments that fall in the following ranges:

3 full pages long

•References are listed in two places.

•The first reference is briefly listed within your answer. This includes identifying information that directs the reader to your List of References at the end of your Written Assignment.

•The second reference is at the end of your work in the List of References section.

•All references cited should provide enough identifying information so that the reader can access the original material.

This paper will be written according to APA Paper style.

Question:

Explain how the presence of a control group accounts for threats to internal validity. Summarize the types of threats to internal validity that can be avoided by utilizing random assignment to control and experimental groups.