Page 148 - DMGT209_QUANTITATIVE_TECHNIQUES_II

Unit 8: Sampling and Sampling Distribution

Introduction Notes

The most important task in carrying out a survey is to select the sample. Sample selection is
undertaken for practical impossibility to survey the population. By applying rationality in
selection of samples, we generalise the findings of our research.
In carrying out a survey relating to the research, we should first select the problem and study its
implications in different areas. Selection of the research problem, as has already been stated,
should be in line with the researcher’s interest, chain of thinking and existing research in the
same area and should have some direct utility. What is most important in selecting a research
problem is that the research topic should be within manageable limits.

8.1 Meaning of Sampling

Sampling is the process of selecting units (e.g., people, organizations) from a population of
interest so that by studying the sample we may fairly generalize our results back to the population
from which they were chosen. Each observation measures one or more properties (weight,
location, etc.) of an observable entity enumerated to distinguish objects or individuals. Survey
weights often need to be applied to the data to adjust for the sample design. Results from
probability theory and statistical theory are employed to guide practice. A sample is a part of a
target population, which is carefully selected to represent the population. Sampling frame is the
list of elements from which the sample is actually drawn. Actually, sampling frame is nothing
but the correct list of population.

8.1.1 Sample Frame

Sampling frame is the list of elements from which the sample is actually drawn. Actually,
sampling frame is nothing but the correct list of population.

Example: Telephone directory, Product finder, Yellow pages.

Did u know? What is the distinction between census and sampling?
Census refers to complete inclusion of all elements in the population. A sample is a
sub-group of the population.
8.1.2 When is a Census Appropriate?

1. A census is appropriate if the size of population is small.

Example: A researcher may be interested in contacting firms in iron and steel or petroleum
products industry. These industries are limited in number, so a census will be suitable.
2. Sometimes, the researcher is interested in gathering information from every individual.

Example: Quality of food served in a mess.

8.1.3 When is Sample Appropriate?

1. When the size of population is large.
2. When time and cost are the main considerations in research.

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