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n 0 = 666

b. Cochran’s formula for calculating sample size when
population size is finite

The formula to determine the sample size for finite population
is as follows:

n =

where,
n = Cochran’s sample size recommendation
0
N = Population size

Suppose we want to calculate the sample size for the population
of our study where, population size is N =13191.
According to the formula (2.1), the sample size will be 666 at
99 percent confidence level with margin of error equal to (0.05).

If is negligible then n is a satisfactory approximation to the
0
sample size. In this case, the sample size (666) exceeds 5 percent
of the population size (13191). So, we need to use the correction
formula to calculate the final sample size.

N = 13191

n = 666
0

n =

n= 634.03= 634

But, if the sample size is calculated at 95 percent confidence
level with margin of error equal to (0.05), the sample size become
384 which does not need correction formula. So, in this case the
representative sample size for our study is 384.

2.2.5 Errors in Sampling

Research results are always subject to some typical error.
Such errors can arise from various sources and have significant
implications for the validity and reliability of study findings.
Researchers need to consider two main factors that can lead to
incorrect inferences: systematic bias and sampling error.

76 SGOU - SLM -MCom Research Methodology