Deck 7: Sampling and Sampling Distributions

Question 1

The primary advantage of cluster sampling is sampling convenience (and possibly less cost).The downside,however,is that the inferences drawn from a cluster sample can be less accurate,for a given sample size,than for other sampling plans.

Answer 1

True

Question 2

In stratified sampling with proportional sample sizes,the proportion of each stratum selected differs from stratum to stratum.

Answer 2

False

Question 3

Cluster sampling is often less convenient and more costly than other random sampling methods.

Answer 3

False

Question 4

When we sample less than 5% of the population,the finite population correction factor; fpc = ,is used to modify the formula for the standard error of the sample mean.

Question 5

Systematic sampling is generally similar to simple random sampling in its statistical properties.

Question 6

A probability sample is a sample in which the sampling units are chosen from the population by means of a random mechanism such as a random number table.

Question 7

The difference between the point estimate and the true value of the population parameter being estimated is called the estimation error.

Question 8

The finite population correction factor is a correction for the standard error when the sample size is fairly large relative to the population size.

Question 9

Simple random sampling can result in under-representation or over-representation of certain segments of the population.This is one of several reasons that simple random samples are almost never used in real applications.

Question 10

The standard error of sample mean is large when the observations in the population are spread out (large ),but that the standard error can be reduced by taking a smaller sample.

Question 11

In stratified sampling,the population is divided into relatively homogeneous subsets called strata,and then random samples are taken from each stratum.

Question 12

One obvious advantage of stratified sampling is that we obtain separate estimates within each stratum - which we would not obtain if we took a simple random sample from the entire population.A more important advantage is that we can increase the accuracy of the resulting population estimates by using appropriately defined strata.

Question 13

Stratified samples are typically not used in real applications because they provide less accurate estimates of population parameters for a given sampling cost.

Question 14

In cluster sampling,the population is divided into subsets called clusters (such as cities or city blocks),and then a random sample of the clusters is selected.Once the clusters are selected,we typically acquire information from all of the members in each selected cluster.

Question 15

We can measure the accuracy of judgmental samples by applying some simple rules of probability.This way,judgmental samples are not likely to contain our built-in biases.

Question 16

Simple random samples are samples in which every possible sample of size n from the population has the same probability of being chosen.

Question 17

A point estimate is a single numeric value,a "best guess" of a population parameter,calculated from the sample data.

Question 18

A list of all members of the population from which we can choose a sample is called a frame,and the potential sample members are called sampling units.

Question 19

In systematic sampling,one of the first k members is selected randomly,and then every k^th member after this one is selected.The value k is called the sampling interval and equals the ratio N / n,where N is the population size and n is the desired sample size.

Question 20

A simple random sample is one where each member of the population has a known chance (this may differ from one member to another)or probability of being chosen.

Question 21

The standard error of an estimate is the standard deviation of the sampling distribution of the estimate.It measures how much estimates from different samples vary.

Question 22

The standard error of the estimate measures how much estimates vary from sample to sample.

Question 23

Nontruthful responses is an example of a nonsampling error.

Question 24

An estimator is said to be biased if the mean of its sampling distribution is not equal to the value of the population parameter being estimated.

Question 25

The sampling distribution of the mean will have the same mean as the original population from which the samples were drawn.

Question 26

The size of a sample can be selected by first determining the desired standard error and then using the formula to calculate n.

Question 27

The central limit theorem (CLT)states that the sampling distribution of the mean is approximately normal,no matter what the distribution of the population,as long as the sample size is large enough.

Question 28

A confidence interval is an interval calculated from the population data,where we strongly believe the true value of the population parameter lies.

Question 29

If the sample size is greater than 30,the Central Limit Theorem (CLT)will always guarantee that the sampling distribution of the sample mean is approximately normal.

Question 30

Voluntary response bias occurs when the responses to questions do not reflect what the investigator had in mind.

Question 31

An unbiased estimate is a point estimate such that the mean of its sampling distribution is equal to the true value of the population parameter being estimated.

Question 32

The sampling distribution of any point estimate (such as the sample mean or proportion)is the distribution of the point estimates we would obtain from all possible samples of a given size drawn from the population.

Question 33

A sample in which the sampling units are chosen from the population by means of a random mechanism is a _____ sample.

A)probability
B)judgmental
C)convenience
D)voluntary response

Question 34

The central limit theorem (CLT)says that as long as the sample size is reasonably large,there is about a 95% chance that the magnitude of the sampling error for the mean will be no more than two standard errors.

Question 35

A judgmental sample is a sample in which the

A)sampling units are chosen using a random number table.
B)quality of sampling units judged before they are added to the sample.
C)sampling units are chosen according to the sampler's judgment.
D)sampling units condemn the sampling method used.

Question 36

It is customary to approximate the standard error of the sample mean by substituting the sample standard deviation s for in the formula: SE( )= .

Question 37

When the sample size is greater than 5% of the population,the formula for the standard error of the mean should be modified with a finite population correction.

Question 38

A sample of size 20 is selected at random from a population of size N.If the finite population correction factor is 0.9418,then N must be 169.

Question 39

The sampling distribution of the mean will have the same standard deviation as the original population from which the samples were drawn.

Question 40

Estimation is the process of inferring the value of an unknown population parameter using data from a random sample drawn from the population.

Question 41

A sampling error is the result of

A)measurement error.
B)nonresponse bias.
C)nontruthful responses.
D)"unlucky" sampling.

Question 42

Which of the following statements correctly describe estimation?

A)It is the process of inferring the values of known population parameters from those of unknown sample statistics.
B)It is the process of inferring the values of unknown sample statistics from those of known population parameters.
C)It is the process of inferring the values of known sample statistics from those of unknown population parameters.
D)It is the process of inferring the values of unknown population parameters from those of known sample statistics.

Question 43

If systematic sampling is chosen as the sampling technique,it is probably because

A)systematic sampling has better statistical properties than simple random sampling.
B)systematic sampling is more convenient.
C)systematic sampling always results in more representative sampling than simple random sampling.
D)systematic sampling gives every possible sample of the same size from the population an equal chance of being selected.

Question 44

The accuracy of the point estimate is measured by its

A)standard deviation.
B)standard error.
C)sampling error.
D)nonsampling error.

Question 45

Which of the following is not a consideration when determining appropriate sample size?

A)the cost of sampling
B)the timely collection of the data
C)interviewer fatigue
D)the likelihood of nonsampling error

Question 46

The sampling mean is the ____ estimate for the population mean .

A)random
B)point
C)simple
D)interval

Question 47

A list of all members of the population is called a

A)sampling unit.
B)probability sample.
C)frame.
D)relevant population

Question 48

Selecting a random sample from each identifiable subgroup within a population is called _____ sampling.

A)simple random
B)systematic
C)stratified
D)cluster

Question 49

A sample chosen in such a way that every possible subset of same size has an equal chance of being selected is called a _____sample.

A)cluster
B)systematic random
C)simple random
D)stratified random

Question 50

When a portion of the sample does not respond to the survey,____ has occurred.

A)a measurement error
B)nonresponse bias
C)a sampling error
D)systematic failure

Question 51

Potential sample members,called sampling units,may be

A)people.
B)companies.
C)households.
D)all of these choices.

Question 52

Which statement is true of proportional sample sizes?

A)The proportion of a stratum in the sample is independent of the proportion of that stratum in the population.
B)The proportion of a stratum in the sample is the same as the proportion of that stratum in the population.
C)The proportion of a stratum in the sample is greater than the proportion of that stratum in the population.
D)The proportion of a stratum in the sample is less than the proportion of that stratum in the population.

Question 53

The standard deviation of is usually called the

A)standard error of the mean.
B)standard error of the sample.
C)standard error of the population.
D)randomized standard error.

Question 54

The key to using stratified sampling is

A)identifying the strata.
B)selecting the appropriate strata.
C)defining the strata.
D)randomizing the strata.

Question 55

Identifiable subpopulations within a population are called

A)clusters.
B)samples.
C)blocks.
D)strata.

Question 56

Which of the following are reasons for why simple random sampling is used infrequently in real applications?

A)Samples can be spread over a large geographic region.
B)Simple random sampling requires that all sampling units be identified prior to sampling.
C)Simple random sampling can result in underrepresentation or overrepresentation of certain segments of the population.
D)All of these choices are valid reasons.

Question 57

The sampling method in which a population is divided into blocks and then selected by choosing a random mechanism is called a _____ sampling.

A)systematic random
B)simple random
C)stratified
D)cluster

Question 58

The probability of being chosen in a simple random sample of size n from a population of size N is

A)1/N.
B)N - 1/n.
C)N/n.
D)n/N.

Question 59

The defining property of a simple random sample is that

A)every possible sample of a particular size has the same chance of being chosen.
B)it is the easiest method to access samples that are chosen.
C)it requires the fewest samples necessary for statistical significance.
D)every k^th subject is chosen as a sample.

Question 60

In sampling,a population is

A)the set of all humans.
B)the set of all members about which a study intends to make inferences.
C)the set of all members from whom data was collected.
D)a random group of individuals,households,cities,or countries.

Question 61

The central limit theorem (CLT)is generally valid for

A)n > 5.
B)n > 10.
C)n > 30.
D)any size n.

Question 62

The opportunity for sampling error is decreased by

A)larger sample sizes.
B)smaller sample sizes.
C)affluent samples.
D)interviewer selected samples.

Question 63

Sampling error is evident when

A)a question is poorly worded and results in bias.
B)the sample is too small.
C)the sample is not random.
D)the sample mean differs from the population mean.

Question 64

The approximate 95% confidence interval for a population mean is

A) .
B) .
C) .
D) .

Question 65

The two basic sources for error when using random sampling are _____ error.

A)sampling and selection
B)identification and selection
C)sampling and nonsampling
D)bias and randomness

Question 66

Which of the following statements are correct?

A)A point estimate is an estimate of the range of a population parameter.
B)A point estimate is a single value estimate of the value of a population parameter.
C)A point estimate is an unbiased estimator if its standard deviation is the same as the actual value of the population standard deviation.
D)All of these choices are correct.

Question 67

The finite population correction factor, ,should generally be used when

A)N is any finite size.
B)n is less than 5% of the population size N.
C)n is greater than 5% of the population size N.
D)n is any finite size.

Question 68

The central limit theorem (CLT)is considered to be an important result in statistics because

A)the CLT allows us to assume that the population distribution is approximately normal,provided n is reasonably large.
B)the CLT allows us to estimate the population mean without knowing the exact form of the population distribution,provided n is reasonably large.
C)the CLT allows us to construct confidence intervals for the population mean without knowing the exact form of the population distribution,provided n is reasonably large.
D)of all of these choices.

Question 69

The opportunity for nonsampling error is larger when the

A)sample size is large.
B)sample size is small.
C)population size is small.
D)population size is large.

Question 70

The approximate standard error of the sample mean is calculated as

A) .
B) .
C) .
D) .

Question 71

Non-truthful response is a particular problem when

A)sensitive questions are asked.
B)surveys are anonymous.
C)interviewers are not trained.
D)the sample is from an unusual population.

Question 72

The averaging effect means that as you average more and more observations from a given distribution,the variance of the average

A)increases.
B)decreases.
C)is unaffected.
D)could either increase,decrease,or stay the same.

Question 73

The mean of the sampling distribution of always equals:

A)the population mean .
B) / n.
C)the population standard deviation .
D) / n.

Question 74

Which of the following statements is correct?

A)A confidence interval describes a range of values that is likely not to include the actual population parameter
B)A confidence interval is an estimate of the range for a sample statistic.
C)A confidence interval is an estimate of the range of possible values for a population parameter.
D)A confidence interval describes a range of values that will always include the actual population parameter.

Question 75

There is an approximately _____% chance that any particular will be within two standard deviations of the population mean ( ).

A)90
B)95
C)99
D)99.7

Question 76

Measurement error occurs when

A)a portion of the sample does not respond to the survey.
B)the sample responses are not clear.
C)the responses to question do not reflect what the investigator had in mind.
D)the investigator does not correctly tally all responses.

Question 77

An unbiased estimator is a sample statistic

A)used to approximate a population parameter.
B)which has an expected value equal to the value of the population parameter.
C)whose value is usually less than the population parameter.
D)that arises from samples that are of size 30 or fewer.

Question 78

The theorem that states that the sampling distribution of the sample mean is approximately normal when the sample size n is reasonably large is known as the _____ theorem.

A)central limit
B)central tendency
C)simple random sample
D)point estimate