Statistics PG510 Practice Questions and Answers
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What is absolute frequency? the number of times the event occurred in an
experiment or study
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Which of the following design modifications assigns confounders
to the treatment and control groups equally? case-control study
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What is statistics? All of these answers.
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What type of variable has a value that describes a measurable
quantity as a number, like "how many" or "how much?" quantitative
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Which of the following sampling methods is an example of
non-probability sampling? Quota sampling
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The value of r is always between what two values? -1 and 1
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Which method of data measurement has both a meaningful zero
value and a defined distance between different measurements? Ratio
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What is the union P(A U B) equivalent to? P(A) + P(B) - P(A 蠩 B)
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What does n represent? Sample
size
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Which of the following is a
convenient way of graphically depicting groups of numerical data through their
five-number summaries (the smallest observation, lower quartile (Q1), median
(Q2), upper quartile (Q3), and largest observation)? box plot
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Given the ages of college students (18, 19, 19, 19, 20, 22, 24),
what is the mean of the class's ages? 20.1
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How does unpaired two-sample t-tests differ from paired? Unpaired tests examine one from each of the
two populations is being compared
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The term central tendency relates to
the way in which quantitative data tend to do what around some value? cluster
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A histogram is an estimate of the probability of what kind of
variable? continuous
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What is statistical inference? The process of drawing conclusions from data that is subject to random
variation.
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In the case of a skewed distribution with outliers, which
measure of central tendency is a more robust statistic? median
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Which of the following would NOT be
considered a potential cause for an outlier? random
sampling
·
The Literary Digest Poll first surveyed only its own readers.
This presented the problem of: under
coverage.
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In this type of experiment, neither the participants nor the
researchers know which participants belong to the control group, as opposed to
the test group. double-blind
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Statistical power is the probability of finding a difference
that ______. does exist
·
Which method is the best for gaining
information about the population of a state? A
census.
Which is true about complementary events? They are mutually exclusive
Which of the following can test for the robustness of
findings from one study under alternative testing conditions or alternative
analyses? study replication
Which of the following best answers the question, "Why
are correlations so useful?" Because
they can indicate a predictive relationship that can be exploited in practice.
How can one tell that Graph A has a larger standard
deviation than Graph B? Graph A is a
wider graph
Which of the following is a study design in which neither
the experimenters nor the subjects know which subjects are in the "test
group" and which are in the "control group"? double-blind
The best way to avoid an unrepresentative sample is to
choose a: random sample.
An example of a sub-population of all high school students
is: all of these answers.
How does one tell if the difference between two values is
significant? If the estimates of two
parameters have confidence intervals at a given ÃŽ³ value that do not overlap
Why did Gosset devise the t-test? As a cheap way to monitor the quality of stout
What type of variable can take a value that can be logically
ordered or ranked? Ordinal
How would a researcher find a relative frequency? divide each frequency by the total number
of data points in the sample
What is the mathematical definition of Pearson's correlation
coefficient? the covariance of two
variables divided by the product of their standard deviations
Quota sampling in 1948:
all of these answers.
What is the importance of understanding normal distribution? All of these answers
What type of variable can take a value based on a count from
a set of distinct whole values? Discrete
Which of the following is suspect of type I errors? Neglecting negative test data
TI=83 graphing calculators are more useful in which of the
following subject functions? Statistics,
trigonometry, and algebra
When data are skewed, which of the following is usually the
most appropriate measure of central tendency? Median
When is the root-mean-square especially useful? when a data set includes both positive and
negative numbers
Which Olympic sport has the largest range in ages?
Gymnastics (17, 18, 18, 19, 20), Swimming (19, 20, 21, 25, 31), or Soccer (22,
22, 30, 32, 32) Swimming
Which method of data measurement differentiates between
items or subjects based only on qualitative classifications they belong to? Nominal
What is a confounding variable? an extraneous variable that correlates with both the dependent and
independent variables
If elements in a sample data set increase arithmetically,
then _____________. the median and
arithmetic mean are equal
Which of the following is NOT a part of the method of least
squares? multiplying all the squared
differences
What are the two characteristics of a statistical
relationship that are shown by scatter plots? direction and strength
Which of the following is characteristic of probability
density functions? It describes the
relative likelihood for a random variable to take on a given value
Which method of data measurement has meaningful distances
between measurements defined, but an arbitrary zero value? Interval
What is a key feature of a skewed distribution with regard
to central tendency? The mean and median
have different values that do not both lie at the center of the curve
Values of r close to either the upper or lower bound of the
coefficient indicates what? a stronger
linear relationship
What field allows us to use a limited sample to make
intelligent and accurate statements about a population? inferential statistics
How does quantitative data differ from qualitative data? Quantitative is in numerical form
Which of the following symbols represents the mean? Μ
Unlike mean and median, the concept of mode also makes sense
for _________. nominal data
How large is the sample size, given a standard deviation of
8 and 95% confidence interval with an error of no more than 3 points? 19.36
Looking at a scatter plot and seeing how close the points
are to a line helps to determine what about the statistical relationship? Strength
Which type of data is original data that has been collected
first hand specially for the purpose in mind? Primary
When the tail on the left side of a histogram is longer than
the right side, a distribution is said to be _________. negatively skewed
What application of exponential distribution determines the
length of a process that can be thought of as a sequence o several independent
tasks? Queuing theory
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