marketing research chapter 6
a good sampling plan includes what 7 steps:
(1) define the target population; (2) select the data collection method; (3) identify the sampling frames needed; (4) select the appropriate sampling method; (5) determine necessary sample sizes and overall contact rates; (6) create an operating plan for selecting sampling units; and (7) execute the operational plan
what 7 factors must a researcher consider in determining the sampling method
(1) research objectives; (2) desired accuracy; (3) availability of resources; (4) time frame; (5) knowledge of the target population; (6) scope of the research; and (7) statistical analysis needs.
what are some advantages of stratified sampling HOMOGENEOUSLY (3)
(1) the assurance of representativeness in the sample; (2) the opportunity to study each stratum and make comparisons between strata; and (3) the ability to make estimates for the target population with the expectation of greater precision and less error
Snowball sampling typically is used in situations where what two things happen
(1) the defined target population is small and unique and (2) compiling a complete list of sampling units is very difficult.
examples of quota sampling:
1)attitudes: e.g., satisfied/dissatisfied, liking/disliking, great/marginal/no quality 2) demographic characteristics (race, gender, income 3) specific behaviors (regular/occasional/rare customer, product user/nonuse)
Three factors play an important role in determining sample sizes with probability designs:
1)the population variance which is a measure of the dispersion of the population, and its square root, referred to as the population standard deviation. 2)The level of confidence desired in the estimate. 3)The degree of precision desired in estimating the population characteristic.
If a researcher wants a sample of 100 to be drawn from a population of 1,000, the skip interval would be
10 because 1000/100=10, then once the skip interval is determined, the researcher would then randomly select a starting point and take every 10th unit until he or she had proceeded through the entire target population list.
what are some disadvantages of cluster samplingIdeally, the people in a cluster should be as heterogeneous as those in the population.
A primary disadvantage of cluster sampling is that the clusters often are homogeneous. The more homogeneous the cluster, the less precise the sample estimates
Simple random sampling requires that __________ sampling units be identified.
ALL
what does e stand for
Acceptable tolerance level of error (stated in percentage points)
disadvantages of quota sampling
An inherent limitation of quota sampling is that the success of the study is dependent on subjective decisions made by researchers. Since it is a nonprobability sampling method, the representativeness of the sample cannot be measured. Therefore, generalizing the results beyond the sampled respondents is questionable.
disadvantages of snowball sampling
As a nonprobability sampling method, it is most useful in qualitative research. But snowball sampling allows bias to enter the study. If there are significant differences between people who are known in certain social circles and those who are not, there may be problems with this sampling technique.
what does n stand for
Calculated sample size determined by the original formula
in this step of developing a sample plan, The researcher must decide how to contact the prospective respondents in the sample. Instructions should be written so that interviewers know what to do and how to handle problems contacting prospective respondents.
Create an Operating Plan for Selecting Sampling Units
Drawing a stratified random sample involves three basic steps: (you have to identify which step a certain example is referring to on the test)
Dividing the target population into homogeneous subgroups or strata. Drawing random samples from each stratum. Combining the samples from each stratum into a single sample of the target population.
what does P stand for
Estimate of expected population proportion having a desired characteristic based on intuition or prior information
what does σμ stand for
Estimate of the population standard deviation (σ) based on some type of prior information
in this step of developing a sample plan, This step is similar to collecting the data from respondents. The important consideration in this step is to maintain consistency and control.
Execute the Operational Plan
advantages of judgment sampling
If the judgment of the researcher is correct, the sample generated by judgment sampling will be better than one generated by convenience sampling. As with all nonprobability sampling procedures, however, you cannot measure the representativeness of the sample in terms of accuracy
in this step of developing a sample plan, the researcher decides how precise the sample estimates must be and how much time and money are available to collect the data.
Step 5: Determine Necessary Sample Sizes and Overall Contact Rates
what are some advantages of systematic sampling
Systematic sampling is frequently used because it is a relatively easy way to draw a sample while ensuring randomness.. availability of lists and the shorter time required to draw a sample versus simple random sampling makes systematic sampling an attractive, economical method for researchers.
is the acceptable amount of error in the sample estimate. For example, if we want to estimate the likelihood of returning in the future to the Santa Fe Grill (based on a Page 1497-point scale), is it acceptable to be within ±1 scale point?
The degree of precision desired in estimating the population characteristic.
what does ZB,CL stand for
The standardized z-value associated with the level of confidence
a popular form of cluster sampling is
area sampling
the clusters are formed by geographic designations.
area sampling
what are some disadvantages of cluster sampling
can be risky. For example, assume a researcher is developing a measure of service quality and in the preliminary stages uses a convenience sample of 300 undergraduate business students. also the data are not generalizable to the defined target population.
primary data is collected from every member of the target population.
census
describes the theoretical characteristics of a sample population
central limit theorem
is similar to stratified random sampling, but is different in that the sampling units are divided into mutually exclusive and collectively exhaustive subpopulations
cluster sampling
is a method in which samples are drawn based on convenience
convenience (ex at shopping malls)
in this step of developing a sample plan, the first task of the researcher is to determine the group of people or objects that should be investigated.
define the target population (step one)
consists of the complete group of elements (people or objects) that are identified for investigation based on the objectives of the research project
defined target population
what is the formula for skip interval
defined target population list size/desired sample size
This approach is used when stratification of the target population produces sample sizes for subgroups that differ from their relative importance to the study.
disproportionately stratified sampling
the sample size selected from each stratum is independent of that stratum's proportion of the total defined target population.
disproportionately stratified sampling
what are some advantages of convenience sampling
enables a large number of respondents to be interviewed in a relatively short time. For this reason, it is commonly used in the early stages of research, including construct and scale measurement development as well as pretesting of questionnaires.
In cluster sampling, each cluster is assumed to be representative of the _________________ of the target population.
heterogeneity
Ideally, the people in a cluster should be as ________________ as those in the population.
heterogeneous
in this step of developing a sample plan, A list of eligible sampling units must be obtained. The list includes information about prospective sampling units (individuals or objects) so the researcher can contact them.
identify the sampling frames needed (step 3)
advantages of snowball sampling
is a reasonable method of identifying respondents who are members of small, hard-to-reach, uniquely defined target populations. As a nonprobability sampling method, it is most useful in qualitative research.
what are some disadvantages of stratified sampling HOMOGENEOUSLY
is determining the basis for stratifying. Secondary information relevant to the required stratification factors might not be readily available, therefore forcing the researcher to use less desirable criteria as the factors for stratifying the target population.
what are some advantages of cluster sampling
is widely used because of its cost-effectiveness and ease of implementation.
sometimes referred to as purposive sampling, respondents are selected because the researcher believes they meet the requirements of the study.
judgment sampling
what is this an example of: sales representatives may be interviewed rather than customers to determine whether customers' wants and needs are changing or to assess the firm's product or service performance.
judgment sampling
Compared to simple random sampling, systematic random sampling is _____________ ________ because it can be done relatively quickly.
less costly
is being used when no single source can generate a large or low incidence sample.
multisource sampling
the probability of selecting each sampling unit is not known. Therefore, sampling error is not known.
non probability sampling
occurs regardless of whether a sample or a census is used.
nonsampling
In this method, consideration is given to the relative size of the stratum as well as the variability within the stratum to determine the necessary sample size of each stratum.
optimal allocation sampling.
is an identifiable group of elements (e.g., people, products, organizations) of interest to the researcher and pertinent to the information problem.
population
what does N stand for
population size
is the acceptable amount of error in the sample estimate.
precision
each sampling unit in the defined target population has a known probability of being selected for the sample.
probability sampling
the sample size from each stratum is dependent on that stratum's size relative to the defined target population. Therefore, the larger strata are sampled more heavily because they make up a larger percentage of the target population.
proportionately stratified sampling
involves the selection of prospective participants according to prespecified quotas for either demographic characteristics
quota sampling
what is another name for snowball sampling
referral sampling
what are the factors to consider in selecting the sampling design
research objectives, degree of accuracy, resources, time frame, knowledge of the population, scope of the research, statistical analysis needs
involves selecting a relatively small number of elements from a larger defined group of elements and expecting that the information gathered from the small group will enable accurate judgments about the larger group.
sampling
is any bias that results from mistakes in either the selection process for prospective sampling units or in determining the sample size
sampling error
After defining the target population, the researcher develops a list of all eligible sampling units, referred to as a
sampling frame
are target population elements actually available to be used during the sampling process.
sampling units
in this step of developing a sample plan, The researcher chooses between probability and nonprobability methods. If the findings will be generalized, a probability sampling method will provide more accurate information than will nonprobability sampling methods
select the appropriate sampling method (step 4)
in this step of developing a sample plan, Using the problem definition, the data requirements, and the research objectives, the researcher chooses a method for collecting the data from the population.
select the data collection method (step 2)
The technique is easily understood and the survey's results can be generalized to the defined target population with a prespecified margin of error. Another advantage is that simple random samples produce unbiased estimates of the population's characteristics.
simple random sampling
This method guarantees that every sampling unit has a known and equal chance of being selected, no matter the actual size of the sample, resulting in a valid representation of the defined target population.
simple random sampling
is a probability sampling procedure. With this approach, every sampling unit has a known and equal chance of being selected.
simple random sampling
what is this an example of: an instructor could draw a sample of ten students from among 30 students in a marketing research class. The instructor could write each student's name on a separate, identical piece of paper and place all of the names in a hat. Each student Page 141would have an equal, known probability of selection. Many software programs including SPSS have an option to select a random sample.
simple random sampling
involves identifying a set of respondents who can help the researcher identify additional people to include in the study
snowball sampling
_______________ sampling is similar to segmentation of the defined target population into smaller, more homogeneous sets of elements.
stratified
involves the separation of the target population into different groups, called strata, and the selection of samples from each stratum.
stratified random sampling
requires that the defined target population be ordered in some way, usually in the form of a customer list, taxpayer roll, or membership roster.
systematic random sampling
a good sampling plan includes these 7 steps:(1) define the ________ population; (2) select the ________ ________ method; (3) identify the sampling ______ needed; (4) select the appropriate sampling method; (5) determine necessary sample sizes and overall ___________ rates; (6) create an ___________ plan for selecting _____________ units; and (7) execute the ____________ plan.
target; data collection; frames; contact; operating, sampling; operational
The primary disadvantage of simple random sampling is
the difficulty of obtaining a complete and accurate listing of the target population elements.
Confidence is the certainty that the true value of what we are estimating falls within the precision range we have selected. For example, marketing researchers typically select a 90 or 95 percent confidence level for their projects. The higher the level of confidence desired is the larger the sample size needed.
the level of confidence desired in the estimate
The population variance, which is a measure of the dispersion of the population, and its square root, referred to as
the population standard deviation.
what is the great weakness of systematic random sampling
the possibility of hidden patterns in the list of names that create bias.
advantages of quota sampling
the sample generated contains specific subgroups in the proportions desired by researchers. quota sampling reduces selection bias by field workers.
what does Q stand for
−[1 − P], or the estimate of expected population proportion not holding the characteristic of interest