This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Transcript
Marketing 6 Chapter 14Sampling Fundamentals Reported by:
Franklin K. Go Raymond A. Gonzales Angelo R. Cantor
Learning Objectives1. Distinguish between a census and a
sample.2. Know the difference between sampling and non-sampling
errors.3. Learn the concept of sampling process.4. Describe
probability and non-probability sampling procedures.5. Determine
sample size with ad-hoc methods.6. Learn to deal with non-response
problems.7. Understand sampling in international context.
Sample or Census A researcher is interested in the
characteristics of the population wherein his potential target
market may reside. The respondents are asked to input necessary
information through surveys called census.
When a Census is Appropriate A census is appropriate if the
sample size is small. Every individual may be included in the
population.
When a Sample is Appropriate A sample is appropriate if the
population is large, the time allotted in obtaining the information
from the population is long and the cost is high.
Error in SamplingError in sampling occurs if there is a gap
between the true value and the observed value of the variable
interest of the population. Sampling Error occurs if the error lies
in the sample parameter and the sample statistics because of
sampling. Non-sampling Error occurs if the error lies in the
population.
Sample ProcessFactors that should be considered when the
decision to use a sample is made: Various steps included in
sampling Major activities with sampling process
Various steps included in sampling
Major activities with sampling process1. Identify the target
population.2. Determine the sampling frame.3. Resolving the
Differences.4. Selecting a sampling procedure.5. Determining the
relevant sample size.6. Obtaining information from respondents.7.
Dealing with the non-response public.8. Generating information for
decision-making purposes.
Determining the Target PopulationThe following should be
considered in determining the target population:1. Look to the
research objectives2. Consider alternatives3. Know your market4.
Consider the appropriate sampling unit5. Specify clearly what is
excluded6. Dont overdefine7. Should be reproducible8. Consider
convenience
Determining the Sampling FrameTasks to do in determining the
sample frame:1. Create lists2. Create lists for telephone
interviewing3. Dealing with population sampling frame
difference
Determining the Sampling FrameThree types of problems when
dealing with population sampling frame difference:1. Subset
problem2. Superset problem3. Intersection problem
Selecting a Sampling Procedure Select between Bayesian Sampling
Procedure and Traditional Sampling Procedure. Decide whether the
sample may have a replacement or not.
Probability SamplingProbability sampling involves four
considerations:1. The target population must be specified.2. The
methods for selecting sample needs to be developed.3. The sample
size must be determined.4. The non-response problem must be
addressed.
Selecting the Probability SampleMethods used to select a
probability sample: Simple Random Sampling Accuracy Cost Trade-off
Stratified Sampling Proportional Stratified Sampling Directly
Proportional Stratified Sampling Inversely Proportional Stratified
Sampling Disproportional Stratified Sampling Cluster Sampling
Systematic Sampling
Multistage Design Cities in Ajax Country City Population
Cumulative Population Concorde 15000 1-15000Mountain View 10000
15001-25000 Filmore 60000 25001-85000 Austin 5000 85001-90000
Cooper 2000 90001-92000 Douglas 5000 92001-97000 Rural Area 3000
97001-100000
Non-probability SamplingThe following are stages where non-
probability sampling is used: 1. Exploratory stage of a research
project 2. Pretesting a questionnaire 3. Dealing with homogeneous
population 4. When researcher lacks statistical knowledge 5. When
operational ease is required
Non-probability SamplingThe following are the four types of
non- probability sampling:1. Judgment2. Snowball3. Convenience4.
Quota
Determining the Sample SizeHow large should the sample be?
Non-response ProblemsThe following are reasons why some of the
populations become non-respondents:1. Refuse to respond2. Lack of
ability to respond3. Not at home4. Inaccessible
What can be done about the non- response problems?1. Improve
the research design to reduce non-responses.2. Repeat the contact
one or more times to reduce non-responses (callbacks).3. Attempt to
estimate the non-response bias.
Shopping Center SamplingShoppers are intercepted and
interviewed personally or through surveys. This method is called
store-intercept interviews.
Shopping Center SamplingShopping Center Selection Selecting a
shopping center is essential because the respondents will be those
who live in the nearby area. The standard of living of the
neighborhood will affect how the sampling will take place and the
types of samples that will be obtained.
Shopping Center SamplingSample Locations within a Center This
is randomly selecting samples through shopping center visits.
Shopping Center SamplingTime Sampling Time segments are devised
when obtaining sample data because of the fact that the time people
go shopping vary from one another.
Shopping Center SamplingSampling People versus Shopping Visits
Researchers should ask the respondents on how often they shop. The
respondents are weighted based on the frequency of visits when
getting the average.