Suppose a research uses the Mann-Whitney test to determine if there is a difference in the volume of text messages sent by a high school student living in a rural area versus an urban area during the month of December.Eight rural high school students and 9 urban high school students were included in the study. If,among all 17,the sum of the ranks W₁ produced from the rural high school students is 72,the U statistic is __________ A) 29 B) 45 C) 90 D) 36 E) 43

Question

Quizplus · Accepted Answer

To calculate the U statistic, we need to first calculate the sum of ranks for the urban high school students. The total number of observations is 8 + 9 = 17. Therefore, the maximum rank sum (U) is (n1*n2)/2 = (8*9)/2 = 36. The sum of ranks for the rural high school students is 72. The sum of ranks for the urban high school students can be calculated as: W₁ = U - 72 U = W₁ + 72 U = 36 - 72 U = -36 However, U cannot be negative, so we use the absolute value: U = |-36| = 36 Therefore, the U statistic is 36. The best choice is D.

Suppose a Research Uses the Mann-Whitney Test to Determine If