Deck 7: Sampling

Question 1

A small value for the coefficient of variation would indicate a relatively homogenous population and that most data points are close to the mean.

Answer 1

True
The smaller the coefficient of variation,the tighter the distribution.

Question 2

In the calculation of confidence levels,non-sampling errors are not accounted for at all.

Answer 2

True
Confidence levels only account for sampling error,not non-sampling errors.

Question 3

Precision expressed in units is called relative precision.

Answer 3

False
Precision expressed in units is called absolute precision.Relative precision is expressed as a percentage.

Question 4

The size of the sample is dramatically more important than the size of the population in almost all statistical calculations in research.

Question 5

Researching with a full census of the population is always more accurate than using only a sample of that population.

Question 6

Judgment sampling is superior to convenience sampling because the sampling error of the former can be ascertained.

Question 7

For almost all variables,Greek letters are used for sample statistics and Roman (e.g.English)letters are used for population parameters.

Question 8

Although stratified sampling can be less costly and easier to conduct,it will almost always have a higher standard error of the estimator than a simple random sample.

Question 9

In probability sampling,the chance that a population element will be included in a sample is equal to that of all other elements.

Question 10

The size of a sample does not necessarily indicate a better study and more accurate results.

Question 11

In sampling terminology,a parameter is any measurement taken of a sample.

Question 12

As the sample size increases,the confidence interval around a mean will also become larger.

Question 13

Although simple random sampling is the simplest of the probability-based sampling procedures,it is not used in marketing research projects as much as other sampling methods,because of a higher probability of non-sampling error.

Question 14

Statistical theory,specifically the central limit theorem,tells us that we can be 68 percent certain that the true population mean lies within one standard error from the sample mean.

Question 15

If a quota sample matches the population along known characteristics,then it has been demonstrated to be a valid sample.

Question 16

In practice,the purpose of a sample parameter is to estimate a population statistic.

Question 17

Quota samples are useful in preliminary stages of research.If done with great care,they can provide clear,accurate,and useful information,even if they are likely to be less valid than a probability sample.

Question 18

If a researcher takes a census of a population,then the finite population correction factor would be equal to 1,because the sample would include all of the population.

Question 19

Although sampling errors tend to decrease with sample size,non-sampling errors tend to increase with sample size.

Question 20

The most common elements in marketing research sampling are business entities.

Question 21

_______________ sampling involves explicit steps to model a population on some prespecified "control" characteristic,typically demographic.

A) Stratified sampling
B) Judgment sampling
C) Quota sampling
D) Simple random sampling

Question 22

Some quantity of interest in a specific population is a

A) parameter
B) statistic
C) variance
D) range

Question 23

Which of the following is a example of judgment sampling?

A) For a major launch campaign for a brand of bath soap, three cities in California were selected because there were deemed to be representative of the nation as a whole.
B) In a study of taste preferences for brands of soft drinks, a marketing research firm selected a sample of 200 people from a large Chicago shopping mall over one weekend.
C) All of the department stores within 50 miles of the corporate office were selected for testing a new point-of-purchase display.
D) From a list of all freshmen at a university, the school selected every 12th name to be interviewed about their first year experience at the school.

Question 24

One advantage of using stratified sampling is that researchers can obtain the same precision as with an unstratified sample,but with a smaller sample and thus at a lower cost.

Question 25

Any quantity derived from a sample is a

A) parameter
B) statistic
C) variance
D) range

Question 26

A _______________ is,loosely speaking,what researchers wish to make inferences about but for which researchers lack the resources (time,funds,energy)to conduct a full census.

A) sampling units
B) study population
C) sampling frame
D) sample element

Question 27

The first step of sampling is to define the population.The second step is to

A) physically select the sample
B) mock up likely and extreme data values
C) decide on a sample size
D) identify the sampling frame

Question 28

With simple random sampling,each element of the population

A) has a known chance of being selected that is not necessarily equal
B) has an equal chance of being selected that is not necessarily known
C) has a known and equal chance of being selected
D) has an unknown chance of being selected because the sample is designed through quotas

Question 29

If a quota sample has 3 control characteristics,each of which has 2 categories,the total number of sampling cells required would be

A) 3
B) 5
C) 6
D) 8

Question 30

All of the following are major benefits sampling offers over taking a census except

A) a sample saves money
B) a sample saves time
C) a sample may be more inclusive
D) a sample may be more accurate

Question 31

Systematic sampling is often used in practice because selecting a systematic sample is easy and inexpensive.

Question 32

With non-probability sampling,each element of the population

A) has a known chance of being selected that is not necessarily equal
B) has an equal chance of being selected that is not necessarily known
C) has a known and equal chance of being selected
D) has an unknown chance of being selected

Question 33

One of the disadvantages of the area sampling is that it is limited to one or two stages.

Question 34

With probability sampling,each element of the population

A) has a known chance of being selected that is not necessarily equal
B) has an equal chance of being selected that is not necessarily known
C) has a known and equal chance of being selected
D) has an unknown chance of being selected because the sample is designed through quotas

Question 35

All of the following statements about convenience samples are true except

A) Sampling error cannot be calculated.
B) The sampling unit or element is self-selected.
C) It is not appropriate for exploratory research.
D) Conclusive statements about the results from a convenience sample cannot be made.

Question 36

A three-stage sampling process would require

A) one sampling frame
B) three sampling frames
C) six sampling frames
D) one sampling frame and a tertiary randomizing device

Question 37

In single-stage sampling

A) different levels of sampling are utilized
B) only one characteristic of the sample is measured
C) the sampling units and elements are the same
D) the sample is larger than the population

Question 38

A(n)_______________ is the unit about which we seek information,and it provides the basis of the analysis that marketing researchers undertake.

A) element
B) population
C) sampling unit
D) sampling frame

Question 39

If the groups developed in cluster sampling are exactly as heterogeneous as the population,then the standard error of the cluster sample will be less than that of simple random sampling.

Question 40

Multistage area sampling is much less statistically efficient than simple random sampling.

Question 41

In disproportionate stratified sampling,more data should be collected from the strata cells that

A) are the most homogeneous
B) are the most heterogeneous
C) have the smallest cell sizes
D) have the largest cell sizes

Question 42

The situation where a researcher directly selects groups and then uses all of the elements in the groups is called

A) one-stage cluster sampling
B) two-stage area sampling
C) two-strata stratified sampling
D) one-stage systematic sampling

Question 43

The measure of dispersion of the data around a sample mean is called

A) variance
B) the coefficient of dispersion
C) its degrees of freedom
D) the t statistic

Question 44

The variance of the sample consisting of the values 2,4,6,8,10 is

A) 6
B) 8
C) 10
D) 12

Question 45

With a confidence interval of the sample mean equal to two standard errors,researchers can be _______________ percent certain that the interval contains the true population mean.

A) 50
B) 68
C) 95
D) 99.7

Question 46

Degrees of freedom is the

A) sample size - 1
B) sample size - number of statistics calculated from the same data
C) sample size - number of control characteristics used for the same data
D) sample size - number of variables within the same data

Question 47

For finite populations,the formula used for calculating the standard error of the sampling distribution of the mean must be modified by the _______________.

A) inverse square law
B) standard deviation
C) finite correction factor
D) sample mean $\pm$ the confidence interval

Question 48

If the standard deviation of a statistic X is 4.3 and the sample size is 16,what is the standard error of the sampling distribution for X?

A) 0.269
B) 1.075
C) 8.295
D) 17.2

Question 49

If a researcher wants to improve the precision of a statistic by one decimal point,the sample size would have to increase by _______________ times.

A) five
B) ten
C) 100
D) 1,000

Question 50

To check if the central limit theorem holds for a sample proportion (and therefore can be used for calculating confidence intervals),the value calculated from np(1-p)should be

A) less than 1
B) greater than 5
C) less than 25
D) greater than 30

Question 51

The square root of the sample variance is

A) sigma ( $\sigma$ )
B) the standard deviation
C) the degrees of freedom
D) the half-width of the confidence interval

Question 52

If done correctly,stratified sampling can actually decrease the standard error of the estimator by

A) making sure the strata are more homogeneous on the variables for which statistics will be calculated
B) making sure each strata forms a representative sample of the population
C) decreasing the number of categories within each of the variables for which statistics will be calculated
D) making sure the sample is sufficiently large to ensure a lower sampling error

Question 53

The first step in setting up a stratified sampling plan is to

A) select an independent random sample from each strata
B) analyze the strata for representativeness based on an external criterion variable
C) select every kth element in the sampling frame
D) divide the population into mutually exclusive and collectively exhaustive groups

Question 54

To calculate the "optimal" sample size,all of the following information is needed except

A) precision required
B) level of confidence ( $\alpha$ )
C) estimate of population variance
D) sample mean

Question 55

All statistical tests,such as calculation of the mean and standard error of the sampling distribution can be calculated and are valid under the following condition(s):

A) the population is normal and the sample is any size
B) the population has an unknown distribution and the sample size is at least 30
C) both a and b
D) either a or b

Question 56

The coefficient of variation is the ratio of the

A) standard error of the sampling distribution to the mean
B) standard deviation to the mean
C) variance to the mean
D) standard deviation to the variance

Question 57

All of the following statements are true of the required sample size,except that

A) it varies inversely with the precision desired
B) it varies directly with the estimate of the population standard deviation
C) if varies inversely with the size of the population
D) it varies directly with the desired confidence level

Question 58

Suppose a researcher is conducting a bivariate analysis with 5 categories for each variable in the cross-tabulation.Using the practical rule of thumb,what is the recommended minimum total sample size?

A) 30
B) 125
C) 150
D) 500

Question 59

When simple random samples are taken from each strata of a stratified sample based on population proportions,it is called

A) simple stratified sampling
B) random stratified sampling
C) proportionate stratified sampling
D) probability proportionate to size sampling

Question 60

The population mean of a continuous variable is denoted by which of the following symbols?

A) $\bar { X }$
B) s
C) s²
D) ( $\mu$ )
E) ( $\sigma$ )

Question 61

Explain the two primary ways a researcher can be assured that each element in an area sample has an equal chance of being selected.

Question 62

In cluster sampling the groups should

A) be homogeneous
B) be heterogeneous
C) contain at least 30 cases
D) reduce the within-group variability

Question 63

How many sampling cells would be required for a quota sampling based on the following control characteristics?
Age: 18-25,26-40,41-60,and 61+
Income: Less than $20,000,$20,000-$39,999,and $40,000-$59,999.
Education: Less than high school,High School,2-year degree,and 4-year degree

Question 64

How does the within-sample variance differ between stratified sampling and cluster sampling?

Question 65

The situation where a researcher directly selects groups and then randomly selects elements from within the selected groups is called

A) one-stage area sampling
B) two-stage cluster sampling
C) two-strata stratified sampling
D) two-stage systematic sampling

Question 66

All of the following methods of sampling require a complete and accurate list of the elements of the population except

A) simple random sampling
B) stratified sampling
C) systematic sampling
D) area sampling

Question 67

Outline the fives steps in selecting a sample.

Question 68

The major problem with systematic sampling is _______________,which means that the list of elements forming the sampling frame forms a cyclical pattern that coincides with a multiple of the size of the sampling interval.

A) regularity
B) periodicity
C) multistaging
D) proportionality

Question 69

In _______________ sampling,the researcher selects every kth element in the frame,after a random start somewhere within the first k elements.

A) random
B) systematic
C) area
D) stratified

Question 70

What is the relation of one,two,and three "standard errors" to the percent confidence interval?

Question 71

Discuss the various implications of the central limit theorem to the practice of sampling.

Question 72

A properly defined population must be defined in what four terms? Give an example.

Question 73

What are absolute and relative precision?

Question 74

For the following values,calculate the mean,variance,and standard deviation.
Data: 6,8,9,12,15

Question 75

Discuss the constraints that affect sample size decisions.