Stat 252
Exam 1
Rein
Fall 2008
1)
Identify each statement about independent samples T-tests and CIs as True or False.
a.
The higher the confidence level, the higher the margin of error.
b.
The higher the sample sizes, the higher the margin of error.
c.
The higher the standard deviations, the higher the margin of error.
d.
If a Confidence Interval for
ߤ
ଵ
െ ߤ
ଶ
includes zero and if
ݔ
ҧ
ଵ
is larger than
ݔ
ҧ
ଶ
, a null hypothesis of equality would
be rejected in favor of an alternative hypothesis of inequality.
e.
If a Confidence Interval for
ߤ
ଵ
െ ߤ
ଶ
includes zero and if
ݔ
ҧ
ଵ
is larger than
ݔ
ҧ
ଶ
, a null hypothesis of equality would
be rejected in favor of an alternative hypothesis that
ߤ
ଵ
is larger than
ߤ
ଶ
.
f.
If a Confidence Interval for the difference of means is 2.1±1.1, it should be interpreted in plain English as “We
are 95% sure that
ݔ
ҧ
ଵ
െ ݔ
ҧ
ଶ
is in the 1.0 to 3.2 range.”
g.
If a Confidence Interval for the difference of means is 2.1±1.1, doubling the sample size for each group would cut
the margin of error approximately in half.
1a
True
1b
False
1c
True
1d
False
1e
False
1f
False
1g
False

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