Whatstatistical test did the researchers use to determine if there was astatistically significant difference in levels of self-esteem betweenthe boys and the girls?

Theresults of the statistical test done show that t-value was present,which provides a clue that t-test was used by the researchers inestablishing if self-esteem levels were statistically significantbetween adolescent boys and girls. Because there was no indicationconcerning the relationship of the boys and girls, it is likely thatunmatched two-sample t-test was used (Stern, 2012).

Whatwas the purpose of calculating a Cohen`s d? When is a Cohen`s dcalculated? Interpret d=.90. What does it mean in this example?

Thepurpose of calculating the Cohen’s d was to determine the meandifference between boys and girls in standard deviation units. TheCohen’s d is calculated when two groups involved in the statisticaltesting have similar standard deviations as well as similarity insize (Gravetter &amp Wallnau, 2013). The meaning of effect size maytend to vary by context however, the interpretation offered by Cohenis that the effect size is large when d ≥ 0.8 moderate when d ≥0.5 small when d ≥ 0.2 (Gravetter &amp Wallnau, 2013). In theexample, d = 0.9 which implies that the mean difference between theboys and girls is large since in this case d = 0.9 and 0.9 &gt 0.8.

Whatif the researcher compared the adolescent boys before treatment andagain after treating them for depression? What type of t-test wouldbe most appropriate in this case, and why?

Incase the researcher wanted to compare the adolescent boys beforetreatment and after treating them for depression, the type of t-testthat would be most appropriate in this case would be the matched pairt-test. This type of t-test would be most appropriate because similarsubjects (adolescent boys) would be exposed to different treatments(Tavakoli,2013).


Gravetter,J.F. &amp Wallnau, B.L. (2013). Essentialsof Statistics for the Behavioral Sciences.London: Cengage Learning.

Stern,R. M. (2012). Quantitativeanalysis of newly evolving patterns of international trade:Fragmentation, offshoring of activities, and vertical intra-industrytrade.Singapore: World Scientific.

Tavakoli,H. (2013). Adictionary of research methodology and statistics in appliedlinguistics.Tehran: Rahnamā.