Laughter among deaf signers. The Journal of Deaf Studies and Deaf Education (Fall 2006) published an article on vocalized laughter among deaf users of American Sign Language (ASL). In videotaped ASL conversations among deaf participants, 28 laughed at least once. The researchers wanted to know if they laughed more as speakers LO5

(while signing) or as audience members (while listening).

For each of the 28 deaf participants, the number of laugh episodes as a speaker and the number of laugh episodes as an audience member were determined. One goal of the research was to compare the mean numbers of laugh episodes of speakers and audience members.

a. Explain why the data should be analyzed as a paired difference experiment.

b. Identify the study’s target parameter.

c. The study yielded a sample mean of 3.4 laughter episodes for speakers and a sample mean of 1.3 laughter episodes for audience members. Is this sufficient evidence to conclude that the population means are different?

Explain.

d. A paired difference t-test resulted in t = 3.14 and p@value 6 .01. Interpret the results in the words of the problem.