E. succession sampling

74. In the Harris Poll Online, which of the following procedures are NOT used to maintain the reliability and integrity in the sample?

a. password protection

b. reminder invitations

c. sharing a summary of the survey findings is used as an incentive for respondents to participate

d. a and c only

e. a, b and c are all procedures used (difficult, page 343)

75. According to the text, all of the following are challenges faced in implementing a sampling design in international research EXCEPT:

a. individuals responsible for making or influencing decision may vary

b. in developing an appropriate sampling frame one cannot rely on high-quality secondary data as one can in developed countries

c. equivalence of samples can elude the researcher

d. probability sampling techniques are uncommon overseas

e. non-governmental organizations are needed for implementing the sampling design in some countries of the world (difficult, page 345)

Essay Questions

76. In a short essay, list and discuss the five steps in the sampling design process.

Answer

a. Define the target population – sampling design begins by specifying the target population. It is essential that the researcher precisely define the target population if the data generated are to address the marketing research problem. Defining the target population involves translating the research problem into a precise statement of who should and should not be included in the sample. The target population should be defined in terms of elements, sampling units, extent, and time frame.

B.Determine the sampling frame – a sampling frame is a representation of the elements of the target population. It consists of a list or set of directions for identifying the target population. A sampling frame can come from the telephone book, a computer program for generating telephone numbers, an association directory listing the firms in an industry, a mailing list purchased from a commercial organization, a city directory, or a map. If a listing is not readily available, it must be compiled.

c. Select a sampling technique – selecting a sampling technique involves choosing nonprobability or probability sampling.

d. Determine the sample size – determining the sample size involves both qualitative and quantitative considerations. Important qualitative factors that the researcher should consider in determining the sample size are (1) the importance of the decision, (2) the nature of the research, (3) the number of variables, (4) the nature of the analysis, (5) sample sizes used in similar studies, and (6) resource constraints. As a general rule, the more important the decision, the more precise the information must be.

e. Execute the sampling process – execution of the sampling process refers to implementing the various details of the sample design. The population is defined, the sampling frame is compiled, and the sampling units are drawn using the appropriate sampling technique so as to achieve the required sample size.

(difficult, pages 325-329)

77. In a short essay, discuss the difference between nonprobability sampling and probability sampling. Include a specific example of each type of sampling to support your answer.

Answer

a. Nonprobability sampling relies on the personal judgment of the researcher, rather than chance, in selecting sample elements. The researcher may select the sample arbitrarily, based on convenience, or make a conscious decision about which elements to include in the sample. Examples of nonprobability sampling include interviewing people at street corners, in retail stores, or in the malls. While nonprobability sampling produces good estimates of population characteristic, these techniques are limited. There is no way to objectively evaluate the precision of the sample results.

b. In probability sampling, sampling elements are selected by chance, that is, randomly. The probability of selecting each potential sample from a population can be prespecified. While every potential sample need not have the same probability of selection, it is possible to specify the probability of selecting a particular sample of a given size. An example of a probability sample is a randomly drawn lottery. Confidence intervals can be calculated around the sample estimates, and it is meaningful to statistically project the sample results to the population, that is, draw inferences about the target population.

(moderate, pages 327-328)

78. In a short essay, list and discuss the four commonly used nonprobability sampling techniques used in marketing research.

Answer

a. Convenience samplingattempts to obtain a sample of elements based on the convenience of the researcher. The selection of sampling units is left primarily to the interviewer. Often, respondents are selected because they happen to be in the right place at the right time. Examples of convenience sampling are (1) use of students, church groups, and members of social organizations, (2) mall intercept interviews conducted without qualifying the respondent, (3) department stores using charge account lists, (4) tear-out questionnaires included in magazines, (5) "people on the street" interviews, and (6) Internet browsers.

b. Judgmental sampling is a form of convenience sampling in which the population elements are selected based on the researcher's judgment. The researcher chooses the sampling elements because she or he believes they represent the population of interest. Common examples of judgmental sampling include (1) test markets selected to determine the potential of a new product, (2) purchase engineers selected in industrial marketing research because they are considered to be representative of the company, (3) bellwether precincts selected in voting behavior research, (4) expert witnesses used in court, and (5) department stores selected to test a new merchandising display system.

c. Quota samplingintroduces two stages to the judgmental sampling process. The first stage consists of developing control categories, or quotas, of population elements. Once the quotas have been assigned, the second stage of the sampling process takes place. Elements are selected using a convenience or judgment process. There is considerable freedom in selecting the elements to be included in the sample.

d. In snowball sampling, an initial group of respondents is selected, usually at random. After being interviewed, these respondents are asked to identify others who belong to the target population of interest. This process is continued, resulting in a snowball effect as one referral is obtained from another. Thus, the referral process effectively produces the sampling from which respondents are selected.

(moderate, pages 330-334)

79. In a short essay, list and discuss the four probability sampling techniques used in marketing research.

Answer

a. In simple random sampling,each element in the population has a known and equal probability of selection. Furthermore, each possible sample of a given size has a known and equal probability of being the sample actually selected. The implication in a random sampling procedure is that each element is selected independently of every other element.

b. In systematic sampling,the sample is chosen by selecting a random starting point and then picking every ith element in succession from the sampling frame. The frequency with which the elements are drawn, i, is called the sampling interval. It is determined by dividing the population size N by the sample size n and rounding to the nearest integer.

c. Stratified sampling involves a two-step sampling process, producing a probability rather than a convenience or judgment sample. First, the population is divided into subgroups called strata. Every population element should be assigned to one and only one stratum, and no population elements should be omitted. Second, elements of each stratum are then randomly selected. A major objective of stratified sampling is to increase precision without increasing cost.

d. In cluster sampling,the target population is first divided into mutually exclusive and collectively exhaustive subpopulations, or clusters. Then a random sample of clusters is selected, based on a probability sampling technique. For each selected cluster, either all the elements are included in the sample or a sample of elements is drawn probabilistically. If all the elements in each selected cluster are included in the sample, the procedure is called one-stage cluster sampling. If a sample of elements is drawn probabilistically from each selected cluster, the procedure is two-stage cluster sampling.

(difficult, pages 334-339)

80. In a short essay, discuss the considerations that should be made when choosing between nonprobability sampling versus probability sampling for a market research study.

Answer

Choosing between nonprobability and probability samples is based on considerations such as the nature of the research, the error contributed by the sampling process relative to the nonsampling error, variability in the population, and statistical and operational considerations. For example, in exploratory research the findings are treated as preliminary and the use of probability sampling may not be warranted. On the other hand, in conclusive research in which the researcher wishes to generalize results to the target population, as in estimating market shares, probability sampling is favored. Probability samples allow statistical projection of the results to a target population.

(easy, pages 339-341)

81. In a short essay, discuss online intercept and online recruited sampling techniques.

Answer

a. Online intercept sampling. Visitors to a Web site are intercepted and given an opportunity to participate in the survey. The interception can be made at the one or more Web sites, including high traffic sites such as Yahoo!. In nonrandom sampling, every visitor is intercepted. This may be meaningful if the Web site traffic is low and the survey has to be completed in a short time and no incentive is being offered. However, this results in a convenience sample. Quotas can be imposed to improve representativeness. In random intercept sampling, the software selects visitors at random and a "pop-up" window asks whether the person wants to participate in the survey. The selection can be made based on simple random or systematic random sampling. If the population is defined as Web site visitors, then this procedure results in a probability sample (simple random or systematic, as the case may be). However, if the population is other than Web site visitors, then the resulting sample is more similar to a nonprobability sample. Nevertheless, randomization improves representativeness and discourages multiple responses from the same respondent.

b. Online recruited sampling- Internet panels.These function in ways similar to nonInternet panels as discussed in Chapters 3 and 5 and share many of the same advantages and disadvantages. In recruited panels, members can be recruited online or even by traditional means (mail, telephone). Based on the researcher's judgment, certain qualifying criteria can be introduced to prescreen the respondents. They are offered incentives for participation such as sweepstake prizes, redeemable points, and other types of Internet currencies. Members typically provide detailed psychographic, demographic, Internet usage, and product consumption information at the time of joining. Opt-in panels operate similarly except that members choose to opt-in as opposed to being recruited. To select a sample, the online company sends an e-mail message to those panelists who qualify based on sample specifications given by the researcher. All of the sampling techniques can be implemented using both types of Internet panels. The success of probability sampling techniques depends upon the extent to which the panel is representative of the target population. Highly targeted samples can be achieved, e.g., teenage girls who shop in malls more than twice a month.

c. Online recruited sampling- Nonpanel. These techniques request potential respondents go online to answer a survey. To illustrate, a computer store such as CompUSA may hand its customers a flier that directs them to a specific password protected site to respond to a questionnaire. If the populations is defined as the company's customers, as in a customer satisfaction survey, and a random procedure is used to select respondents, a probability sample will be obtained. Other nonpanel approaches involve the use of e-mail lists that have been rented from suppliers. Presumably, these respondents opted-in or gave permission for their e-mail addresses to be circulated. Offline techniques such as short telephone screening interviews are also used for recruiting Internet samples. Several companies routinely collect e-mail addresses in their customer relationship databases by obtaining that information from customer telephone interactions, product registration cards, on-site registrations, special promotions, and so on.

(moderate, pages 342-344)

Chapter 13 – Sampling: Final and Initial Sample

Size Determination

Date: 2016-01-14; view: 1405