Page 76 - DMGT404 RESEARCH_METHODOLOGY

Research Methodology

Notes Deliberate or Purposive Sampling

This is also known as the judgment sampling. The investigator uses his discretion in selecting
sample observations from the universe. As a result, there is an element of bias in the selection.
From the point of view of the investigator, the sample thus chosen may be a true representative
of the universe. However, the units in the universe do not enjoy an equal chance of getting
included in the sample. Therefore, it cannot be considered a probability sampling.

Example: Test market cities are being selected, based on the judgment sampling, because
these cities are viewed as typical cities matching with certain demographical characteristics.
Judgment sample is also frequently used to select stores for the purpose of introducing a new
display.

Shopping Mall Intercept Sampling

This is a non-probability sampling method. In this method the respondents are recruited for
individual interviews at fixed locations in shopping malls.

Example: Shopper's Shoppe, Food World, Sunday to Monday.
This type of study would include several malls, each serving different socio-economic population.

Example: The researcher may wish to compare the responses of two or more TV commercials
for two or more products. Mall samples can be informative for this kind of studies. Mall samples
should not be used under following circumstances i.e., if the difference in effectiveness of two
commercials varies with the frequency of mall shopping, change in the demographic characteristic
of mall shoppers, or any other characteristic. The success of this method depends on "How well
the sample is chosen".

Sequential Sampling

This is a method in which the sample is formed on the basis of a series of successive decisions.
They aim at answering the research question on the basis of accumulated evidence. Sometimes,
a researcher may want to take a modest sample and look at the results. Thereafter, s(he) will
decide if more information is required for which larger samples are considered. If the evidence
is not conclusive after a small sample, more samples are required. If the position is still
inconclusive, still larger samples are taken. At each stage, a decision is made about whether
more information should be collected or the evidence is now sufficient to permit a conclusion.

Example: Assume that a product needs to be evaluated.
A small probability sample is taken from among the current user. Suppose it is found that
average annual usage is between 200 to 300 units. It is known that the product is economically
viable only if the average consumption is 400 units. This information is sufficient to take a
decision to drop the product. On the other hand, if the initial sample shows a consumption level
of 450 to 600 units, additional samples are needed for further study.

Quota Sampling

Quota sampling is quite frequently used in marketing research. It involves the fixation of
certain quotas, which are to be fulfilled by the interviewers.

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