Learning Objectives
1. To understand the different stages involved in the sampling process.
2. To identify the key steps in selecting a sample.
3. To learn how to define and identify the target population.
4. To recognize the importance of sampling in research
5. To apply knowledge of sampling stages to real-world scenario
Stages of Sampling
Sampling is a crucial step in the context of research.
The selection of sample is a crucial research decision. The process of sampling
involves certain stages. These stages are also known as sample design. Sample
design is a specific plan for obtaining a sample from a given population. It
refers to the technique or procedure the researcher would adopt in selecting
items for the sample. It is the responsibility of the investigator to make sure
of the reliability, appropriateness, and authenticity of the sample design.
Characteristics of a Good Sample Design
A
good sample design should have certain characteristics. The sample design must
result in a truly representative sample. Sample design must have small sampling
error. The given sample design must be viable in the context of budget
availability. Sample design must be such so that systematic bias can be
controlled. Sample should be such that the results of the study can be general
with a reasonable level of confidence (Kothari 2004: 56-58).
Identifying the Target
Population
The first step in the sampling process is to identify
the target population. The target population refers to the large group of
individuals or elements that the researcher wishes to generalize the results of
the study to. In other words, it is the population that the researcher is
interested in learning about or describing.
Example 1: Teachers in the Jawahar Navodaya Vidyalaya Samiti
For instance, if a researcher is interested in learning about the
teachers in the Jawahar Navodaya Vidyalaya Samiti system, all the teachers who
teach within that system would constitute the target population.
Example 2: Indian Adolescents
In another example, if a researcher is interested in studying the
attitudes and values of Indian adolescents, the target population would be all
Indian boys and girls in the age range of 10 to 19 years, assuming that
adolescence is operationally defined as the period between ages 10 and 19 years.
Distinguishing Between Target Population and
Accessible Population
It is essential to distinguish between the target
population and the accessible population. The accessible population refers to
the population of subjects that are accessible to the researcher for drawing a
sample. In most research studies, researchers deal with accessible populations
rather than the target population.
Example: Sampling Indian Adolescents
For example, it would be expensive and time-consuming to sample from the
total population of Indian adolescents. However, a researcher could draw a
sample of adolescents from one state. In this case, the accessible population
would be the adolescents from that particular state, and the researcher could
only generalize the results to adolescents in that state, not to all Indian
adolescents.
Population and Sample
Select the Sampling Frame
Once the population has been identified, the next step
is to select the sampling frame. A sample frame is drawn from the target
population. A sampling frame is a list of the actual cases from which sample
will be drawn. Thus the sampling frame must be representative of the
population. In brief, sampling frame is a list of all the items in the
population.
Choose
Sampling Technique
In general, sampling techniques can be divided into
two types- probability sampling and non-probability sampling.
Probability Sampling
Probability
sampling involves selecting a sample in which the elements are drawn by chance
procedures. The main characteristic of probability sampling is that every
member or element of the population has a known probability of being chosen in
the sample. This type of sampling is also known as random sampling.
Non-probability Sampling
Non-probability sampling, on the other hand, includes methods of
selection in which elements are not chosen by chance procedures. The success of
non-probability sampling depends on the knowledge, expertise, and judgment of
the researcher. Non-probability sampling is used when the application of
probability sampling is not feasible. Its advantages include convenience and
economy.
Table 1
Basic Sample Designs
|
|
Representation Basis |
|
|
Probability sampling |
Non-probability sampling |
|
|
Unrestricted sampling |
Simple random sampling |
Haphazard sampling or convenience sampling |
|
Restricted sampling |
Complex random sampling (such as cluster sampling, systematic sampling,
stratified sampling ) |
Purposive sampling(such as quota sampling, judgement
sampling) |
Determine Sample Size
After
selecting the sample technique, the investigator must determine the sample
size. The researcher should also consider factors like desired precision,
confidence level, population variance and budget constraints.
Field Work and Data
Collection
Once
target population, sampling frame, sampling technique and sample size have been
established, the next step is to conduct fieldwork and collect data.
Response rate is the number of cases agreeing to take part in the study.
These cases are taken from original sample. In reality, most researchers never
achieve a 100 percent response rate. Reasons for this might include refusal to
respond, ineligibility to respond, inability to respond, or the respondent has
been located but the researchers are unable to make contact. In sum, response
rate is important because each non response is liable to bias the final sample.
Figure 2
Stages of Sampling
References
Ary, D., Jacob,
L. C., Sorenson, C., & Razavieh, A. (2010). Introduction to Research in Education (8th ed.).
Wadsworth Cengage Learning.
Cohen, L., Manion, L., & Morrison, K. (2007). Research Methods in Education (6th
ed.) Routledge.
Creswell, J.
(2012). Educational Research (4th
ed.). Pearson.
Gay, L.R., Mills, G., & Airasian, P. (2012). Educational Research (10th
ed.). Pearson.
Kothari, C.R.
(2004). Research Methodology: Methods and
Techniques (2nd ed.). New Age International Publishers.
Kumar, D.
(Eds.). (2019). Methodology of
Educational Research and Statistics. Lovely Professional University.
Kumar, R. (2011). Research
Methodology (3rd ed.). SAGE.
Little, T.D. (Eds.). (2013). The Oxford Handbook of Quantitative Methods. OXFORD UNIVERSITY
PRESS.
Singh, Y.K. (2006).
Fundamentals of Research
Methodology and Statistics. New Age International Publishers.
Wu, C., & Thompson, M. (2012). Sampling Theory and Practice. Springer.
Get ready to explore the fascinating world of sampling! In this interactive blog post, I will take you through the stages of sampling, from defining population to selecting sample.
Dive into the comic strip for a visual introduction, and don't miss the humorous take on sampling with a special meme. For a more in-depth look, check out PowerPoint presentation, which breaks down each stage in detail.
Listen to the curated Spotify playlist, featuring tunes to help you grasp the concepts. Flip through the interactive FlipHTML5 publication for a immersive learning experience.
And for a video explanation, watch YouTube video, which walks you through the stages of sampling with engaging visuals and examples.
Let's get started on this sampling adventure!"
Sampling struggles are real!
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Population and Sample
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