Web Calculator Exercise 3
T test for independent groups and
dependent groups (Two-group 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
H0 and Ha for this study.
d. Conduct
the appropriate analysis. Should H0 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
H0 and Ha for this study.
d. Conduct
the appropriate analysis. Should H0 be rejected?
3. A
researcher is interested in whether listening to music helps or hinders
test-performance. To control for differences in cognitive level, this
researcher decides to use a within-participants 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 20-item 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
interval-ratio 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
H0 and Ha for this study.
d. Conduct
the appropriate analysis. Should H0 be rejected? What should the
researcher conclude?
e. Calculate
the 95 confidence interval.
