Page 65 - DMGT404 RESEARCH_METHODOLOGY

Unit 4: Sampling Design

Notes
Example: You want to learn about scooter owners in a city. The RTO will be the frame,
which provides you names, addresses and the types of vehicles possessed.
3. Specify the sampling unit: Individuals who are to be contacted are the sampling units. If
retailers are to be contacted in a locality, they are the sampling units.

Sampling unit may be husband or wife in a family. The selection of sampling unit is very
important. If interviews are to be held during office timings, when the heads of families
and other employed persons are away, interviewing would under-represent employed
persons, and over-represent elderly persons, housewives and the unemployed.
4. Selection of sampling method: This refers to whether

(a) probability or
(b) non-probability methods are used.
5. Determine the sample size: This means we need to decide "how many elements of the
target population are to be chosen?" The sample size depends upon the type of study that
is being conducted. For example: If it is an exploratory research, the sample size will be
generally small. For conclusive research, such as descriptive research, the sample size will
be large.
The sample size also depends upon the resources available with the company.

Did u know? Sample size depends on the accuracy required in the study and the permissible
errors allowed.
6. Specify the sampling plan: A sampling plan should clearly specify the target population.
Improper defining would lead to wrong data collection.

Example: This means that, if a survey of a household is to be conducted, a sampling plan
should define a "household" i.e., "Does the household consist of husband or wife or both",
minors etc., "Who should be included or excluded." Instructions to the interviewer should include
"How he should obtain a systematic sample of households, probability sampling non-probability
sampling". Advise him on what he should do to the household, if no one is available.

7. Select the sample: This is the final step in the sampling process.

4.2.1 Characteristics of a Good Sample Design

A good sample design requires the judicious balancing of four broad criteria - goal orientation,
measurability, practicality and economy.

1. Goal orientation: This suggests that a sample design "should be oriented to the research
objectives, tailored to the survey design, and fitted to the survey conditions". If this is
done, it should influence the choice of the population, the measurement as also the
procedure of choosing a sample.
2. Measurability: A sample design should enable the computation of valid estimates of its
sampling variability. Normally, this variability is expressed in the form of standard
errors in surveys. However, this is possible only in the case of probability sampling. In
non-probability samples, such a quota sample, it is not possible to know the degree of
precision of the survey results.

LOVELY PROFESSIONAL UNIVERSITY 59