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Math 115 - Inference II (Ch8) Flashcards | StudBud
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Math 115 - Inference II (Ch8)
Math 115 - Inference II (Ch8)
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Math 115 - Ch9
Flashcards
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Answers
1
When the "degrees of freedom" is infinitely large, the t-distribution is the same as the Z~N(0, 1) distribution.
false
true
2
The sample mean is
all of the above
unbiased, if the sample is a random sample
the arithmetic average of a sample of data
an estimate of a population mean
3
There are 3 basic pairs of hypotheses. The two-tailed one-sample t-test has the following hypo:
H0: μ ≠ μ0 and Ha: μ = μ0
H0: μ = μ0 and Ha: μ > μ0
H0: μ = μ0 and Ha: μ < μ0
H0: μ = μ0 and Ha: μ ≠ μ0
4
The standard deviation of the sampling distribution is what we call the standard error.
True
False
5
A sampling distribution is a probability distribution of a statistic.
False
True
6
There are 3 basic pairs of hypotheses. The 1-tailed (left) 1-sample t-test has the following hypo:
H0: μ = μ0 and Ha: μ > μ0
H0: μ = μ0 and Ha: μ ≠ μ0
H0: μ ≠ μ0 and Ha: μ = μ0
H0: μ = μ0 and Ha: μ < μ0
7
When comparing two populations (matched pairs), the samples are
not random samples
paired (dependent) samples
independent samples
paired-independent samples
8
The sampling distribution of the sample mean is approximately Normal (if the population was normal).
false
true
9
The standard error of the sample mean, gets smaller with larger sample size.
false
true
10
A confidence interval can be interpreted as a range of values for the population parameter.
false
true
11
Compared to the z-distribution, the t-distribution has
more peaks
taller peaks
thinner tails
thicker tails
12
Which of the following value(s) for the significance level α is a good choice?
.10
.01
.05
all of the above
13
If curve B shows a t-distribution, which curve could NOT show a normal distribution?
curve C
curve A
14
The t-distribution’s shape depends on only
all of the above
degrees of freedom
mean
standard deviation
15
Hypotheses are always statements about population statistics.
false
true
16
A Simple Random Sample (SRS) of size n = 18 formed the following histogram. Should we conduct a hypothesis test?
Yes, because we used a random method to collect his data.
No, n too small for Central Limit Theorem.
17
A Simple Random Sample of arriving trains of size n = 21 ( the number of minutes late). Is a t-procedure ok to use?
No, because the sample size is not large enough.
Yes, because the data show no strong skewness or outliers.
18
Which of the following are way(s) in which we can report a confidence interval?
both A and B above
Mean ± standard deviation
Estimate ± margin of error
(lower boundary, upper boundary)
19
Which of the following are example(s) of when dependence occurs?
all of the above
when the objects are related somehow
when the experimenters have deliberately matched subjects
“before and after” comparisons
20
In hypothesis testing, values of the t-statistic that are far from 0 tend to discredit the null hypo.
false
true
