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