stats final
A continuous random variable may assume
all values in an interval or collection of intervals.
Two events are mutually exclusive
if they have no sample points in common
In a one-tailed hypothesis test (lower tail), the test statistic is determined to be -2. The p-value for this test is
.0228
Which of the following is not an example of descriptive statistics?
An estimate of the number of Alaska residents who have visited Canada
If the data distribution is symmetric, the skewness is
0
In a standard normal distribution, the probability that Z is greater than zero is
0.5
As the sample size becomes larger, the sampling distribution of the sample mean approaches a
Normal distribution
The union of events A and B is the event containing all the sample points belonging to
A or B or both
Which of the following sampling methods does not lead to probability samples?
Convenience sampling
Which of the following is a graphical summary of a set of data in which each data value is represented by a dot above the axis?
Dot plot
Which of the following is an example of nonprobabilistic sampling?
Judgment sampling
Which of the following is a characteristic of the standard normal probability distribution?
The standard deviation must be 1
Which of the following is not a characteristic of the normal probability distribution?
The standard deviation must be 1
Whenever the probability is proportional to the length of the interval in which the random variable can assume a value, the random variable is
Uniformly distributed
Which of the following is not a measure of central location?
Variance
Social security numbers consist of numeric values. Therefore, social security number is an example of
a categorical variable
The weight of an object is an example of
a continuous random variable
A single numerical value used as an estimate of a population parameter is known as
a point estimate
If we consider the simple random sampling process as an experiment, the sample mean is
a random variable
If arrivals follow a Poisson probability distribution, the time between successive arrivals must follow
an exponential probability distribution.
In interval estimation, as the sample size becomes larger, the interval estimate
becomes narrower
As the number of degrees of freedom for a t distribution increases, the difference between the t distribution and the standard normal distribution
becomes smaller.
A probability distribution showing the probability of x successes in n trials, where the probability of success does not change from trial to trial, is termed a
binomial probability distribution.
In a questionnaire, respondents are asked to mark their gender as male or female. Gender is an example of a(n)
categorical variable
The fact that the sampling distribution of sample means can be approximated by a normal probability distribution whenever the sample size is large is based on the
central limit theorem.
The median is a measure of
central location
When the assumption of equally likely outcomes is used to assign probability values, the method used to assign probabilities is referred to as the
classical method.
In point estimation
data from the sample is used to estimate the population parameter.
As the sample size increases, the margin of error
decreases
The summaries of data, which may be tabular, graphical, or numerical, are referred to as
descriptive statistics
The Poisson probability distribution is a
discrete probability distribution.
The number of customers that enter a store during one day is an example of
discrete random variable
There is a lower limit but no upper limit for a random variable that follows the
exponential probability distribution
When data are positively skewed, the mean will usually be
greater than the median.
The most common graphical presentation of quantitative data is a
histogram
The standard deviation of a standard normal distribution
is always equal to one.
The probability that a continuous random variable takes any specific value
is equal to zero
The value added to and subtracted from a point estimate in order to develop an interval estimate of the population parameter is known as the
margin of error
In a standard normal distribution, the
mean is 0 and the standard deviation is 1
In computing the standard error of the mean, the finite population correction factor is used when
n/N > 0.05
The variance can never be
negative
As the degrees of freedom increase, the t distribution approaches the
normal distribution
For the interval estimation of μ when σ is known and the sample is large, the proper distribution to use is the
normal distribution.
As a rule of thumb, the sampling distribution of the sample proportions can be approximated by a normal probability distribution whenever
np ≥5 and n(1-p) ≥5.
The sum of the relative frequencies for all classes will always equal
one
The scale of measurement that is used to rank order the observation for a variable is called the
ordinal scale
The general form of an interval estimate of a population mean or a population proportion is the _____ plus and minus the _____.
point estimate, margin of error
The purpose of statistical inference is to provide information about the
population based upon information contained in the sample.
Initial estimates of the probabilities of events are known as
prior probabilities.
Doubling the size of the sample will
reduce the standard error of the mean to approximately 70% of its current value
When the results of experimentation or historical data are used to assign probability values, the method used to assign probabilities is referred to as the
relative frequency method
The degrees of freedom associated with a t distribution are a function of the
sample size
The degrees of freedom associated with a t distribution are a function of the
sample size.
The probability distribution of all possible values of the sample proportion p̄ is the
sampling distribution of p̄.
The absolute value of the difference between the point estimate and the population parameter it estimates is the
sampling error.
An important numerical measure of the shape of a distribution is the
skewness
A normal distribution with a mean of 0 and a standard deviation of 1 is called
standard normal distribution
The Department of Transportation of a city has noted that on the average there are 17 accidents per day. The average number of accidents is an example of
statistical inference
A method of assigning probabilities based upon judgment is referred to as the
subjective method.
When s is used to estimate σ, the margin of error is computed by using the
t distribution
If the null hypothesis is rejected in hypothesis testing,
the alternative hypothesis is true
The extent of the sampling error might be affected by all of the following factors except
the expected value of the sample statistic.
Which of the following does not need to be known in order to compute the p-value?
the level of significance
In hypothesis testing, the tentative assumption about the population parameter is
the null hypothesis.
If two events are independent, then
the product of their probabilities gives their intersection.
The measure of variability that is influenced most by extreme values is
the range
A uniform probability distribution is a continuous probability distribution where the probability that the random variable assumes a value in any interval of equal length is
the same for each interval.
For a normal distribution, a positive value of z indicates that
the sample mean is larger than the population mean.
In developing an interval estimate, if the population standard deviation is unknown
the sample standard deviation must be used.
The closer the sample mean is to the population mean
the smaller the sampling error
The addition law is potentially helpful when we are interested in computing the probability of
the union of two events.
A graphical method of representing the sample points of an experiment is a
tree diagram
When a percentage of the smallest and largest values are deleted from a data set, the mean of the remaining data values is the
trimmed mean
To compute the necessary sample size for an interval estimate of a population mean, all of the following procedures are recommended when σ is unknown except
use .5 as an estimate.
A mean computed in such a way that each data value is given a weight reflecting its importance is referred to as a
weighted mean
The __________ can be interpreted as the number of standard deviations a data value is from the mean of all the data values.
z-score
The sample mean is the point estimator of
μ