15. In a particular country, itis known that college seniors report falling in love an
average of 2.20 times duringtheir college years. A sample of five seniors, originally
from that country but who havespent their entire college career in the
United States, were asked howmany times they had fallen in love during their
college years. Their numbers were2, 3, 5, 5, and 2. Using the .05 significance
level, do students like these whogo to college in the United States fall in love
more often than those from theircountry who go to college in their own country?
(a) Use the steps of hypothesistesting. (b) Sketch the distributions involved.
(c) Explain your answer to someonewho is familiar with the Z test
(from Chapter 5) but is unfamiliar with the t testfor a single sample.
18. Twenty students randomlyassigned to an experimental group receive an
instructional program; 30 in acontrol group do not. After 6 months, both groups
are tested on their knowledge.The experimental group has a mean of 38 on the
test (with an estimatedpopulation standard deviation of 3); the control group
has a mean of 35 (with anestimated population standard deviation of 5). Using
the .05 level, what should theexperimenter conclude? (a) Use the steps of
hypothesis testing, (b) sketchthe distributions involved, and (c) explain your
answer to someone who is familiarwith the t test for a single sample but not
with the t test for independent means.
18. A psychologist studyingartistic preference randomly assigns a group of 45 participants
to one of three conditions inwhich they view a series of unfamiliar abstract
paintings. The 15 participants inthe Famous condition are led to believe that
these are each famous paintings;their mean rating for liking the paintings is 6.5
(S = 3.5). The 15 in theCritically Acclaimed condition are led to believe that
these are paintings that are notfamous but are very highly thought of by a group
of professional art critics;their mean rating is 8.5 (S = 4.2 ). The 15 in the Control
condition are given no special informationabout the paintings; their mean rating
is 3.1 (S = 2.9 ). Does whatpeople are told about paintings make a difference
in how well they are liked? Usethe .05 level. (a) Use the steps of hypothesis testing; (c) figure the effectsize for the study; (d) explain your answer to part (a) to someone who isfamiliar with the t test for independent means but is unfamiliar withanalysis of variance
11. Make up a scatter diagramwith 10 dots for each of the following situations:
(a) perfect positive linearcorrelation, (b) large but not perfect positive linear
correlation, (c) small positivelinear correlation, (d) large but not perfect negative
linear correlation, (e) nocorrelation, (f) clear curvilinear correlation.
13. Four young children weremonitored closely over a period of several weeks to
measure how much they watchedviolent television programs and their amount
of violent behavior toward theirplaymates. The results were as follows:
Child Code number
Weekly Viewing of
Violent TV (hours
Number of Violent orAggressive
Acts Toward Playmates
(a) Make a scatter diagram of thescores; (b) describe in words the general pattern of correlation, if any; (c)figure the correlation coefficient; (d) figure whether the correlation isstatistically significant
(use the .05 significance level,two-tailed); (e) explain the logic of what
you have done, writing as if youare speaking to someone who has never heard
of correlation (but who doesunderstand the mean, deviation scores, and hypothesis
testing); and (f) give threelogically possible directions of causality, indicating
for each direction whether it isa reasonable explanation for the correlation
inlight of the variables involved (and why).
Can anyone help me?