Question
In: Statistics and Probability
An independent sample experiment uses 25 participants in one group and 30 participants in the second...
An independent sample experiment uses 25 participants in one group and 30 participants in the second group to compare the two population means. What is the degrees of freedom used in this test ?
a.
25
b.
24
c.
30
d.
29
Solutions
Expert Solution
For testing two population means we have two tests. One is used
when population standard deviations are known and another is used
when population standard deviations are not known. When population
standard deviations are known we use the z test which will not have
any degrees of freedom. But if population standard deviations are
not known we have again two cases is., if the population variances
are assumed equal and population variances are assumed unequal. In
the first case, if population variances are assumed equal, we will
have the t test with df 
where 
is the participants is first group and 
is the participants in the second group. Then according to the
situation here, the df=25+30-2=55-2=53. Which is not given in the
options. Now when population variances are assumed unequal then the
formula for df contains standard deviations of the groups. The
answer mainly is 53.
orchestra answered 1 year agoRelated Solutions
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20
26
29
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20
30
28
26
26
20
27
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21
24
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26
23
33
27
21
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26
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35
35
30
37
35
45
30
55
25
50
20
45
25
43
30
42
24
40
34
36
33
45
37
50
38
41
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