Web Calculator Exercise 3
T test for independent groups and
dependent groups (Twogroup designs)
1.
An LU professor is interested in whether
there is a difference between undergraduate students and graduate students in
the amount of time spent praying each day. The professor gathers information from
random samples of undergraduate and graduate students on the LU campus. The amount of time praying is normally
distributed and is measured on an interval/ratio scale.
Graduate

Undergraduate

15

9

17

11

10

9

13

6

11

5

17

6

a. What
statistical test should be used to analyze the data?
b. Is
this a one or two tailed test?
c. Identify
H_{0} and H_{a} for this study.
d. Conduct
the appropriate analysis. Should H_{0} be rejected?
2.
A
teacher wants to investigate whether there is a difference between male and
female students in the amount of time they spend studying for statistics. The
table below shows the amount of time students spend studying statistics each
week. The amounts of time spent studying are normally distributed.
Male

Female

27

25

25

29

19

18

10

23

16

20

17

15

15

19

a. What
statistical test should be used to analyze the data?
b. Is
this a one or two tailed test?
c. Identify
H_{0} and H_{a} for this study.
d. Conduct
the appropriate analysis. Should H_{0} be rejected?
3. A
researcher is interested in whether listening to music helps or hinders
testperformance. To control for differences in cognitive level, this
researcher decides to use a withinparticipants design. He selects a random
sample of participants and has them study different material of equal
difficulty in both the music and no music conditions. Participants take a 20item quiz on the material. The table
below shows the scores on the quiz. The study is completely counterbalanced to
control for order effects. The scores
obtained are measured on an
intervalratio scale and are normally
distributed.
Music

No Music

17

17

16

18

15

17

16

17

18

19

18

18

a. What
statistical test should be used to analyze the data?
b. Is
this a one or two tailed test?
c. Identify
H_{0} and H_{a} for this study.
d. Conduct
the appropriate analysis. Should H_{0} be rejected? What should the
researcher conclude?
e. Calculate
the 95 confidence interval.
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