Multiple Choice
Identify the
choice that best completes the statement or answers the question.
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1.
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DDT is an insecticide that accumulates up the food
chain. Predator birds can be contaminated with quite high levels of the chemical by eating many
lightly contaminated prey. One effect of DDT upon birds is to inhibit the production of the enzyme
carbonic anhydrase, which controls calcium metabolism. It is believed that this causes eggshells to
be thinner and weaker than normal and makes the eggs more prone to breakage. (This is one of the
reasons why the condor in California is near extinction.) An experiment was conducted where 16
sparrow hawks were fed a mixture of 3 ppm dieldrin and 15 ppm DDT (a combination often found in
contaminated prey). The first egg laid by each bird was measured, and the mean shell thickness was
found to be 0.19 mm. A “normal” eggshell has a mean thickness of 0.2 mm.
The null and alternative hypotheses are
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2.
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A significance test allows you to reject a
hypothesis  in favor of an alternative Ha at the 5% level of significance. What can you say about significance at
the 1% level?
A) |  can be rejected at the 1% level of
significance. | B) | There is
insufficient evidence to reject  at the 1% level of
significance. | C) | There is
sufficient evidence to accept  at the 1% level of
significance. | D) | Ha can be rejected at the 1% level of significance. | E) | The answer can’t be determined from the information
given. |
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3.
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In a test of H0: µ =
100 against Ha: µ  100, a sample of size 80 produces
z = 0.8 for the value of the test statistic. The P-value of the test is thus equal
to
A) | 0.20 | B) | 0.40 | C) | 0.29 | D) | 0.42 | E) | 0.21 |
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4.
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Which of the following is/are
correct?
I. The power of a significance test depends on
the alternative value of the parameter.
II. The
probability of a Type II error is equal to the significance level of the test.
III. Type I and Type II errors make sense only when a significance
level has been chosen in advance.
A) | I and II only | B) | I and III only | C) | II and III
only | D) | I, II, and III | E) | None of the above gives the complete set of correct
responses. |
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5.
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Here's a quote from a medical journal:
“An uncontrolled experiment in 17 women found a significantly improved mean clinical symptom
score after treatment. Methodologic flaws make it difficult to interpret the results of this
study.” The authors of this paper are skeptical about the significant improvement
because
A) | there is no control group, so the improvement might be
due to the placebo effect or to the fact that many medical conditions improve over
time. | B) | the P-value given was P = 0.03,
which is too large to be convincing. | C) | the response
variable might not have an exactly Normal distribution in the population. | D) | the study didn’t use enough subjects to achieve any statistically
significant findings. | E) | the mean is not
resistant. |
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6.
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A medical experiment compared the herb echinacea
with a placebo for preventing colds. One response variable was “volume of nasal
secretions” (if you have a cold, you blow your nose a lot). Take the average volume of nasal
secretions in people without colds to be  = 1. An increase to  = 3 indicates a
cold. The significance level of a test of  versus  is
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7.
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A radio show runs a phone-in survey each morning.
One morning the show asked its listeners whether they would prefer Congress or the president to set
policy for the nation. The majority of those phoning in their responses answered
“Congress,” and the station reported the results as statistically significant. We may
safely conclude that
A) | there is deep discontent in the nation with the
president. | B) | it is unlikely
that, if all Americans were asked their opinion, the result would differ from that obtained in the
poll. | C) | there is strong evidence that the majority of Americans
prefer Congress to set national policy. | D) | very few people
other than the majority of those phoning in their responses prefer Congress to set policy for the
nation. | E) | that the majority of Americans would actually prefer the
president to set policy, because of the biased method of data
collection. |
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8.
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In a test of H0: µ =
100 against Ha: µ  100, a sample of size 10 produces a
sample mean of 103 and a P-value of 0.08. Thus, at the 0.05 level of
significance
A) | there is sufficient evidence to conclude that
µ  100. | B) | there is sufficient evidence to conclude that µ =
100. | C) | there is insufficient evidence to conclude that
µ = 100. | D) | there is
insufficient evidence to conclude that µ  100. | E) | there is sufficient evidence to conclude that µ =
103. |
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9.
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Which of the following is not a condition
for performing inference about a population mean  ?
A) | Inference is based on n independent
measurements. | B) | The population
distribution is Normal or the sample size is large (say n > 30). | C) | To use a z test, we must know the population standard deviation  . | D) | The data are
obtained from an SRS from the population of interest. | E) | Both np and n(1 – p) are 10 or
greater. |
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10.
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Resting pulse rate is an important measure of the
fitness of a person's cardiovascular system, with a lower rate indicative of greater fitness.
The mean pulse rate for all adult males is approximately 72 beats per minute. A random sample of 25
male students currently enrolled in the Faculty of Agriculture was selected and the mean resting
pulse rate was found to be 80 beats per minute with a standard deviation of 20 beats per minute. The
experimenter wishes to test if the students are less fit, on average, than the general
population.
A possible Type II error here would be to
A) | conclude that the students are less fit (on average)
than the general population when in fact they have equal fitness on
average. | B) | conclude that the students have the same fitness (on
average) as the general population when in fact they are less fit (on
average). | C) | conclude that the students have the same fitness (on
average) as the general population when in fact they have the same fitness (on
average). | D) | conclude that the students are less fit (on average)
than the general population, when, in fact, they are less fit (on
average). | E) | conclude that the students have the same fitness (on
average) when in fact they are more fit (on average). |
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