A researcher would like to conduct an experiment to test the effectiveness of a program designed to raise SAT scores.

A researcher would like to conduct an experiment to test the effectiveness of a program designed to raise SAT scores. She wishes to obtain a sample of low-scoring high school students, administer the program, and then administer the SAT again. She hypothesizes that SAT scores will be higher after the program than before.

1.    Provide a clear explanation/definition of "internal validity"

2.    Describe and explain at least four (4) different threats to internal validity that are relevant in this study. Provide a clear and relevant explanation/justification for each of the threat to internal validity identified