Statistics Problem

General Requirements:

Use the following information to ensure successful completion of the assignment:

• Researchers wanted to explore self-esteem in adolescent boys and adolescent girls. They used a 5-point Likert-type self-esteem inventory; 1 = strongly disagree and 5 = strongly agree. What if their results yielded the following: t=1.71, d=.90.
• This assignment uses a grading rubric.
• Prepare this assignment according to the APA guidelines found in the APA Style Guide, located in the Student Success Center. An abstract is not required

Directions:

In an essay of 250-500 words, use the scenario presented in part 1a, above, to thoroughly answer the following questions:

1. What statistical test did the researchers use to determine if there was a statistically significant difference in levels of self-esteem between the boys and the girls?
2. What was the purpose of calculating a Cohen's d? When is a Cohen's d calculated? Interpret d=.90. What does it mean in this example?  
3. What if the researcher compared the adolescent boys before treatment and again after treating them for depression? What type of t-test would be most appropriate in this case, and why?