TEST PROBLEMS
A famous
nonverbal communication scholar believes that anxiety is an important variable
in nonverbal behavior. On the basis of the assumption that anxious people have
more energy than those who are calm, he hypothesizes that anxious people
gesture more often while they talk than do calm people. He tests this
hypothesis by randomly selecting five anxious people and five calm people
(measured on a valid and reliable scale) from a university class. He tells each
research participant to bring a friend to a laboratory where he videotapes 20
minutes of their conversation. He then counts the average number of gestures
per minute made by each research participant. He obtains the following scores:
Anxious
People Calm People
3 4
3 6
4 7
5 9
5 9
A. State the research hypothesis.
B. State the null hypothesis.
C. Is this a one-tailed or a two-tailed test?
D. What are the degrees of freedom?
E. If alpha is set at .05, what is the critical value needed
for rejecting the null hypothesis?
F. What is the t-value?
G. Does the study support the research hypothesis?
Answers to t-test problem #1: (a) Anxious people
gesture significantly more often while talking than calm people; (b) Anxious
people do not differ from calm people in how often they gesture while talking;
(c) one-tailed; (d) 8; (e) 1.86; (f) 2.86; yes, the t-value exceeds the
critical value and warrants rejection of the null hypothesis.
A clever
undergraduate, Grace N. Poise, hypothesizes that people under 30 are more
humorous than people over 30. She tests this hypothesis by randomly selecting 4
people over 30 from the telephone book and 4 people under 30 from university
registration lists. She gives each research participant the Humorous Speech
Scale, which measures humor on a Likert-type scale from 1 to 10. The scores are
listed below.
People
Under 30 People
Over 30
6 5
7 6
10 2
9 3
A. State the research hypothesis.
B. State the null hypothesis.
C. Is this a one-tailed or a two-tailed test?
D. What are the degrees of freedom?
E. If alpha is set at .01, what is the critical value needed
for rejecting the null hypothesis?
F. What is the t-value?
G. Was Ms. Poise's research hypothesis supported?
Answers to t-test problem #2: (a) People under 30 are
more humorous than people over 30; (b) People under 30 do not differ from
people over 30 in ability to be humorous; (c) one0-tailed; (d) 6; (e) 3.14);
(f) 4.38; (g) yes
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