Sampling in marketing research

Basics of sampling I
• A sample is a part of a whole to show what the rest like
• Sampling helps to determine the corresponding value of the population and plays a vital role in marketing researchSamples offer many benefits
• Save costs: less expensive to study the sample than the population
• Save time: less time needed to study the sample than population
• Accuracy: since sampling isdone with care and studies are conducted by skilled and qualified interviewers, the results are expected to accurate
• Destructive nature of elements: for some elements, sampling is the way to test,since test destroys the element itself.
Basics of sampling II
Limitations of sampling
• Demands more rigid control to undertaking sample operation
• Minority and smallness in number of sub groupsoffer suspected
• Accuracy level may be affected when data is subjected to weighting
• Sample results are good approximations at best
Sampling process
1. Defining the population
a. Universe orpopulation is the whole mass under study
b. How to define a universe
i. What constitutes the units of analysis (HDB apartments)?
ii. What are the sampling units (HDB apartments occupied in the lastthree months)?
iii. What is the specific designation of the units to be covered (HDB to town area)?
iv. What time period does the data refer to?
2. Developing a sampling frame
a. A sample frame isthe list of all elements in the population (such as telephone directories, electoral registers, club membership etc.) from which the samples are drown
b. A sample frame which does not fully representan intended population will result in frame error and affect the degree of reliability of sample result
3. Determining sample size
a. Sample size may be determined by using:
i. Subjective methods(less sophisticated methods)
1. The rule of thumb approach: e.g. 5% of the population
2. Conventional approach: e.g. average of sample sizes of similar other studies
3. Cost basis approach: the...