Marketing Chapter 12 Twelve Sampling Designs And Sampling Procedures Part Four Sampling Designs And

Chapter Twelve: Sampling Designs and Sampling Procedures

Part Four

Sampling Designs and Sampling Procedures

Chapter 12

Sampling Designs and Sampling Procedures

AT-A-GLANCE

I. Introduction

II. Why Sample?

A. Pragmatic reasons

B. Accurate and reliable results

C. Destruction of test units

III. Identifying a Relevant Population and Sampling Frame

A. Defining the target population

B. The sampling frame

2. Online panels

3. Sampling frames for international marketing research

C. Sampling units

IV. Random Sampling and Nonsampling Errors

A. Random sampling error

B. Systematic sampling error

1. Systematic but not obvious sampling error

a. Website visitors

b. Panel samples

c. Opting in

C. Less than perfectly representative samples

V. Probability versus Nonprobability Sampling

A. Convenience sampling

B. Judgment sampling

C. Quota sampling

2. Advantages of quota sampling

D. Snowball sampling

E. Probability Sampling

F. Simple random sampling

G. Systematic sampling

H. Stratified sampling

I. Proportional versus disproportional sampling

J. Cluster sampling

Chapter Twelve: Sampling Designs and Sampling Procedures

K. Multistage area sampling

VI. What Is the Appropriate Sample Design?

A. Degree of accuracy

B. Resources

C. Time

D. Advance knowledge of the population

E. National versus local project

LEARNING OUTCOMES

1. Explain reasons for taking a sample rather than a complete census.

3. Compare random sampling and systematic (nonsampling) errors with an emphasis on how the

Internet is intertwined with this issue.

5. Summarize various types of probability samples.

6. Discuss how to choose an appropriate sample design.

CHAPTER VIGNETTE: Harvest Time Domaine Chandon

Napa Valley’s Domaine Chandon is the USA’s largest producer of sparkling wine. The company,

whose parent company Moet & Chandon is among the largest Champagne producers in France as

well as the owners of the prestigious Dom Perignon brand, produces millions of bottles of Napa

Valley sparkling wine annually. Sampling is a highly relevant topic to the wine industry and takes

place in numerous forms. Perhaps no sample is more critical, though, than the sample used to

SURVEY THIS!

Students are asked to look at the survey that asks a variety of questions of college students and to

imagine that they are an online university interested in studying the habits of college students in

general. They are then asked to answer the following questions:

1. How well do the results collected from this survey represent the market for undergraduate

college students?

2. How well do the results represent American undergraduate college students?

3. How well to the results represent American business students?

Chapter Twelve: Sampling Designs and Sampling Procedures

➢ Crowdsourced panels (such as M-Turk) involve consumers who opt-in and provide little

ability for generalization in the vast majority of marketing and consumer research settings.

➢ Convenience samples do have appropriate uses in marketing research. Convenience samples

(including student samples) are particularly appropriate when:

• Exploratory research is conducted.

➢ When cost and time constraints only allow a convenience sample:

➢ The research report should address the adequacy of the sample. The report should qualify

OUTLINE

I. INTRODUCTION

A. A sample is a subset or some part of a larger population.

B. Purpose of sampling is to estimate an unknown characteristic of a population.

C. Sampling is defined in terms of the population being studied.

II. WHY SAMPLE?

A. Pragmatic Reasons

2. Sampling cuts costs, reduces labor requirements, and gathers vital information

quickly.

B. Accurate and Reliable Results

1. Most properly selected samples give results that are reasonably accurate.

3. A sample on occasion is more accurate than a census – interviewer mistakes,

tabulation errors, and other nonsampling errors may increase during a census

because of the increased volume of work.

C. Destruction of Test Units

1. Many research projects, especially those in quality-control testing, require the

destruction of the items being tested.

III. IDENTIFYING A RELEVANT POPULATION AND SAMPLING FRAME

A. Defining the Target Population

1. Once the decision to sample has been made, the first question concerns

part, except for use as permitted in a license distributed with a certain product or service or otherwise on a

password-protected website for classroom use.

4. When there is no list of population elements, the sampling unit is generally

something other than the population element. For example, in a random-digit

dialing study the sampling unit will be telephone numbers.

IV. RANDOM SAMPLING AND NONSAMPLING ERRORS

A. If a difference exists between the value of a sample statistic of interest and the value

of the corresponding population parameter, a statistical error has occurred.

B. Two basic causes of differences between statistics and parameters:

2. systematic (nonsampling) errors

C. Random sampling error is the difference between the sample result and the result of

a census conducted using identical procedures.

E. Random Sampling Error

1. Random sampling error is a technical term that refers only to statistical

2. Random sampling error is a function of sample size.

3. As sample size increases, random sampling error decreases.

a. When someone releases poll results and describes them with a margin of

error of 3, 5, or 10 percent, that margin of error is determined by the sample

size.

F. Systematic Sampling Error

2. These errors are not due to chance fluctuations.

4. Errors due to sample selection problems are nonsampling errors and should not

be classified as random sampling errors.

5. Systematic But Not Obvious Sampling Error

a. Internet surveys allow researchers to reach a large sample rapidly – both an

advantage and a disadvantage.

c. Website Visitors

i. Many Internet surveys are conducted with volunteer respondents who

visit an organization’s website intentionally or by happenstance.

Chapter Twelve: Sampling Designs and Sampling Procedures

part, except for use as permitted in a license distributed with a certain product or service or otherwise on a

password-protected website for classroom use.

(a) It is possible to over-represent the more frequent visitors to the site,

and thus represents site visits rather than visitors.

(b) There are several programming techniques and technologies that can

help accomplish more representative sampling based on site traffic

(i.e., “cookies,” registration data, or pre-screening).

d. Panel Samples

i. Consumer panels provide a practical sampling frame in many situations.

ii. There is some concern regarding the representativeness of these samples,

are not fully accessible via the Internet, it uses a propensity-weighting

scheme to ensure that survey results are representative. The research

company does parallel studies – phone as well as Internet – to test the

accuracy of its Internet data gathering capabilities.

e. Opting In

i. Opt in—to give permission to receive selected e-mail, such as

questionnaires, from a company with an Internet presence.

ii. It is important not to send unauthorized e-mail to respondents.

iii. Spamming is not tolerated by experienced Internet users and can

iv. Sites like Amazon’s Mechanical Turk provide another opportunity

for respondents to opt in to surveys.

(a) However, these respondents do not participate as members of

any panel but rather as an unscreened, paid respondent.

(b) Therefore, respondents who participate after coincidentally or

intentionally finding a survey on a website of this type are not

random and cannot be considered representative of the general

consumer population.

G. Less than Perfectly Representative Samples

1. Random sampling errors and systematic errors associated with the sampling

2. Additional errors will occur if individuals refuse to be interviewed or cannot be

contacted.

V. PROBABILITY VERSUS NONPROBABILITY SAMPLING

A. Several alternative ways to take a sample are available.

B. The main alternative sampling plans may be grouped into two categories:

2. Nonprobability techniques

C. In probability sampling, every element in the population has a known, nonzero

probability of selection.

part, except for use as permitted in a license distributed with a certain product or service or otherwise on a

password-protected website for classroom use.

D. In nonprobability sampling, the probability of any particular member of the

population being chosen is unknown.

1. The selection of sampling units in nonprobability sampling is quite arbitrary, as

researchers rely heavily on personal judgment.

3. Therefore, projecting the data beyond the sample is technically speaking,

statistically inappropriate.

4. Nevertheless, nonprobability samples are pragmatic and are used in market

research.

E. Convenience Sampling

2. Researchers generally use convenience samples to obtain a large number of

3. Research looking for cross-cultural differences in organizational or consumer

behavior typically uses convenience samples.

F. Judgment Sampling

1. Judgment (purposive) sampling is a nonprobability technique in which an

2. The consumer price index (CPI) is based on a judgment sample of market-basket

3. Test-market cities often are selected because they are viewed as typical cities

whose demographic profiles closely match the national profile.

G. Quota Sampling

1. The purpose of quota sampling is to ensure that the various subgroups in a

2. In quota sampling, the interviewer has a quota to achieve.

3. Aggregating the various interview quotas yields a sample representing the

desired proportion of the subgroups.

a. Possible Sources of Bias

i. The logic of classifying the population by pertinent subgroups is

essentially sound.

ii. However, because respondents are selected according to a convenience

b. Advantages of Quota Sampling

i. The major advantages over probability sampling are:

(a) speed of data collection

(b) lower costs

(c) convenience

Chapter Twelve: Sampling Designs and Sampling Procedures

ii. Although there are many problems with this method, careful supervision

of the data collection may provide a representative sample for analyzing

the various subgroups within a population.

H. Snowball Sampling

1. Snowball sampling refers to a variety of procedures in which initial respondents

3. Reduced costs and sample sizes are clear-cut advantages of snowball sampling.

4. However, bias is likely to enter into the study because a person suggested by

6. Since the focus group is not expected to be a generalized sample, snowball

1. All probability sampling techniques are based on chance selection procedures,

2. Randomness characterizes a procedure whose outcome cannot be predicted

because it depends on chance.

4. There are several probability sampling techniques discussed below.

J. Simple Random Sampling

1. A simple random sample is a sampling procedure that assures that each element

3. When populations consist of large numbers of elements, tables of random

4. Selecting a random sample: to use a table of random numbers, a serial number is

assigned to each element of the population. Then, assuming a population of

5. The random-digit dialing technique of sample selection requires that the

researcher identify the exchange or exchanges of interest (the first three numbers)

and then use a table of numbers to select the next four numbers.

K. Systematic Sampling

1. Simple process.

2. An initial starting point is selected by a random process; then every nth number

Chapter Twelve: Sampling Designs and Sampling Procedures

part, except for use as permitted in a license distributed with a certain product or service or otherwise on a

password-protected website for classroom use.

a. A simplified rule of thumb for understanding the concept of optimal

allocation is that the stratum sample size increases for strata of larger sizes

with the greatest relative variability.

J. Cluster Sampling

1. The purpose of cluster sampling is to sample economically while retaining the

characteristics of a probability sample.

2. In a cluster sample, the primary sampling unit is no longer the individual

4. Cluster sampling is classified as a probability sampling technique because of

5. Cluster samples frequently are used when lists of the sample population are not

available.

7. A problem may arise with cluster sampling if the characteristics and attitudes of

the elements within the cluster are too similar.

N. Multistage Area Sampling

1. Multistage area sampling involves two or more steps that combine some of the

probability techniques already described.

3. The Bureau of the Census provides maps, population information, demographic

VI. WHAT IS THE APPROPRIATE SAMPLE DESIGN?

A. A researcher who must decide on the most appropriate sample design for a specific

B. Degree of Accuracy

1. The degree of accuracy required or the researcher’s tolerance for sampling and

C. Resources

1. The cost associated with the different sampling techniques varies tremendously.

3. Managers concerned with the cost of the research versus the value of the

D. Time

1. Researchers who need to meet a deadline or complete a project quickly will be

more likely to select simple, less time-consuming sample designs.

Chapter Twelve: Sampling Designs and Sampling Procedures

E. Advance Knowledge of the Population

1. In many cases, a list of population elements will not be available to the

researcher.

F. National versus Local Project

2. When population elements are unequally distributed geographically, a cluster

sample may become much more attractive.

QUESTIONS FOR REVIEW AND CRITICAL THINKING/ANSWERS

1. If you decide whether you want to see an entire movie based on a 90 second YouTube clip,

are you using a sampling technique? Could this be described as a scientific sampling

technique? Explain your answer.

2. What is the difference between a population and a sample? What are the reasons why a

sampling process is so often used in place of a census? Why is it that a population can

sometimes be as accurate as, or more accurate than, a census?

3. Define sample, sampling unit, sampling frame and population.

A sample is a subset or some part of a larger population.

Chapter Twelve: Sampling Designs and Sampling Procedures

i. High school students who may consider architecture as a career.

6. Describe the differences between a random and systematic sampling error.

A random sampling error is the difference between the sample result and the result of a census

7. What is a nonprobability sample? What are some examples?

8. Is a convenience sample ever appropriate? Explain.

9. When would a researcher use a judgment, or purposive, sample?

Chapter Twelve: Sampling Designs and Sampling Procedures

b. A quota sample of 50 light users and 50 heavy users of beer in a shopping mall intercept

study

c. A sample of regular Twitter users to explore social network links

Step one would be to generate a list of Twitter users; a tall order, given the large

d. A stratified sample of 50 mechanical engineers, 40 electrical engineers, and 40 civil

engineers from the subscriber list of an engineering journal.

16. Selection for jury duty is supposed to be a totally random process. Comment on the following

computer selection procedures, and determine if they are indeed random:

a. A program instructs the computer to scan the list of names and pluck names that are next

to those from the last scan.

drivers. If the weight information listed on the license matches the random number, the

person is selected.

Chapter Twelve: Sampling Designs and Sampling Procedures

c. The juror source list is obtained by merging a list of registered voters with a list of

licensed drivers.

17. Provide an example of marketing research in which a sample that is truly representative of all

of North America is needed. If you cannot provide an actual example, try to contrive a

situation that would require such a sample. How often would such a target population be

needed?

18. [Ethics Question] To ensure a good session, a company gathers focus group members from a

list of articulate participants instead of conducting random sampling The client did not

inquire about sample selection when it accepted the proposal. Is this ethical?

21. [Internet Question] Go to http://www.reversephonedirectory.com and put in your phone

number. How accurate is their database? When might it be useful to generate a list of names

and numbers for a telephone survey?

22. [Internet Question] Go to the U.S. Census Bureau’s home page at http://www.census.gov,

click on quick facts. You can find profiles of every state from this website. Suppose a

representative sample of the state of Louisiana is used to represent the current U.S.

population. How well does Louisiana represent the United States overall? How well does

Louisiana represent California or Maine? Use the profiles of the states and of the country to

form your opinion. If a researcher is resource limited and uses only a single state to help

predict success of a new product to be launched nationally, how should he or she go about

discussing generalizability of the research results?

Chapter Twelve: Sampling Designs and Sampling Procedures

Students should be able to find information about Louisiana by searching “Louisiana.” Students’

responses will vary because there is a considerable amount of information available from which

they can describe their “profiles.”

RESEARCH ACTIVITY

1. Develop a sampling plan to study the lunch habits of undergraduate and graduate students of

your university. Research questions involve who has the most market share and what are the

preferred food types and price points for this particular school. Explain your choices.

CASE 12.1 Who’s Fishing?

Objective: To enable students to develop a sampling plan.

Summary: Although interest groups express concerns about the impact of saltwater fishers on

the fish population, no one really knows how many people fish for recreation or how many fish

Questions

1. Imagine that an agency or business has asked for help in gathering data about the number of

sports anglers who fish off the coast of Georgia. What advice would you give about

sampling? What method or combination of methods would generate the best results?

part, except for use as permitted in a license distributed with a certain product or service or otherwise on a

password-protected website for classroom use.

2. What other criteria besides accuracy would you expect to consider? What sampling methods

could help you meet those criteria?