Research Methods –STA630 VU
© Copyright Virtual University of Pakistan 87
Lesson 26
SAMPLE AND SAMPLING TERMINOLOGY
A sample is a subset, or some part, of a larger whole. A larger whole could be anything out which
sample is taken. That ‘whole’ could be a bucket of water, a bag of sugar, a group of organizations, a
group of students, a group of customers, or a group mid-level managers in an organization. A complete
group of entities sharing some common set of characteristics is population. In other words, the totality
out of which sample is drawn is referred to as population.
Why sample?
1. Saves Cost, Labor, and Time
Applied research projects usually have budget and time constraints. Since sample can save financial cost
as well as time, therefore, to go for sample study is pragmatic.
Of course, a researcher investigating a population with an extremely small number of population
elements may elect to conduct a study on the total population rather than a sample because cost, labor,
and time constraints are relatively insignificant.
Although sample study cuts costs, reduces labor requirements, and gathers vital information quickly, yet
there could be other reasons.
2. Quality Management/supervision
Professional fieldworkers are a scarce commodity. In a large study rather than employing less qualified
staff it may be advisable to do a sample study and employ highly qualified professional fieldworkers. It
can certainly affect the quality of the study. At the same time it may be easier to manage a small group
and produce quality information. Supervision, record keeping, training, and so forth would all be more
difficult in a very large study.
3. Accurate and Reliable Results
Another major reason for sampling is that samples, if properly selected, are sufficiently accurate in most
of the cases. If the elements of a population are quite similar, only a small sample is necessary to
accurately portray the characteristics of interest. Most of us have had blood samples taken from the
finger, the arm, or another part of body. The assumption is that blood is sufficiently similar through out
the body, the characteristics of the blood can be determined on the basis of sample.
When the elements of population are highly homogenous, samples are highly representative of the
population. Under these circumstances almost any sample is as good as another.
Samples may be more accurate than census. In a census study of large population there is a greater
likelihood of non-sampling errors. In a survey mistakes may occur that are unrelated to the selection of
people in the study. For example, a response may be coded incorrectly, or the keyboard operator might
make data entry error. Interviewer mistakes, tabulation errors, and other non-sampling errors may
increase during census because of the increased volume of work. In sample increased accuracy is
possible because the fieldwork and tabulation of the data can be closely supervised than would be
possible in a census. In field survey, a small, well trained, closely supervised group may do a more
careful and accurate job of collecting information than a large group of nonprofessional interviewers
trying to contact everyone.
4. Sampling may be the Only Way
Many research projects, especially those in quality control testing, require the destruction of the items
being tested. If the manufacturer of firecrackers wished to find out whether each product met a specific
production standard, there would be no product left after testing. Similarly, consider the case of electric
docsity.com
