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In a study of the credibility of eyewitness testimony, at least two independent raters view video tapes and make ratings. What is the purpose of comparing these ratings?

A) to increase the internal validity B) to aid in making operational definitions C) to establish test-retest reliability D) to establish interrater reliability

Tamara has just finished collecting her data for her research methods final project. Her results indicate that there is a statistically significant difference between the means of the groups. In this situation, Tamara should __________

a. fail to reject the null hypothesis. b. reject the null hypothesis. c. Both A and B d. None of the above