Basically, two costs are involved in a sampling analysis, which govern the selection of a sampling procedure. They are:
Criteria For Selecting A Sampling Procedure:
Basically,
two costs are involved in a sampling analysis, which govern the selection of a
sampling procedure. They are:
1. The cost of data collection, and
2. The cost of drawing incorrect inference from the selected data.
There are two causes of incorrect
inferences, namely systematic bias and sampling error. Systematic bias arises
out of errors in the sampling procedure. They cannot be reduced or eliminated
by increasing the sample size. Utmost, the causes of these errors can be
identified and corrected. Generally, a systematic bias arises out of one or
more of the following factors: 1. Inappropriate sampling frame, 2. Defective measuring device, 3. Non-respondents, 4. Indeterminacy principle, and 5. Natural bias in the reporting of data. Sampling error refers to the
random variations in the sample estimates around the true population
parameters. Because they occur randomly and likely to be equally in either
direction, they are of compensatory type, the expected value of which errors
tend to be equal to zero. Sampling error tends to decrease with the increase in
the size of the sample. It also becomes smaller in magnitude when the
population is homogenous. Sampling error can be computed
for a given sample size and design. The measurement of sampling error is known
as ‘precision of the sampling plan’. When the sample size is increased, the
precision can be improved. However, increasing the sample size has its own
limitations. The large sized sample not only increases the cost of data
collection, but also increases the systematic bias. Thus, an effective way of
increasing the precision is generally to choose a better sampling design, which
has smaller sampling error for a given sample size at a specified cost. In
practice, however, researchers generally prefer a less precise design owing to
the ease in adopting the same, in addition to the fact that systematic bias can
be controlled better way in such designs. In sum, while selecting the
sample, a researcher should ensure that the procedure adopted involves a
relatively smaller sampling error and helps to control systematic bias.
Tags : Research Methodology - Introduction
Last 30 days 10183 views