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Unformatted text preview: ments determined at
random.
For example, if we want to select a sample of 50 students
from 500 students under this method Kth item is picked up from the
sampling frame and K is called the sampling interval.
N Population size
Sampling interval , K =
=
n
Sample size
500
= 10
50
K = 10 is the sampling interval. Systematic sample consists
in selecting a random number say i K and every K th unit
K= 21 subsequently. Suppose the random number ‘ i’ is 5, then we select
5, 15, 25, 35, 45,…… The random number ‘ i’ is called random
….
start. The technique will generate K systematic samples with equal
probability.
Merits :
1. This method is simple and convenient.
2. Time and work is reduced much.
3. If proper care is taken result will be accurate.
4. It can be used in infinite population.
Limitations:
1.Systematic sampling may not represent the whole population.
2.There is a chance of personal bias of the investigators.
Systematic sampling is preferably used when the
information is to be collected from trees in a forest, house in
blocks, entries in a register which are in a serial order etc.
Exercise – 2
I. Choose the best Answer:
1. Sampling is inevitable in the situations
(a) Blood test of a person
(b) When the population is infinite
(c) Testing of life of dry battery cells
(d) All the above
2. The difference between sample estimate and population
parameter is termed as
(a) Human error
(b) Sampling error
(c) Nonsampling error
(d) None of the above
3. If each and every unit of population has equal chance of being
included in the sample, it is known as
(a) Restricted sampling
(b) Purposive sampling
(c) Simple random sampling (d) None of the above
4. Simple random sample can be drawn with the help of
(a) Slip method
(b) Random number table
(c) Calculator
(d) All the above
22 5. A selection procedure of a sample having no involvement of
probability is known as
(a) Purposive sampling
(b) Judgement sampling
(c) Subjective sampling
(d) All the above
6. Five establishments are to be selected from a list of...
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 Winter '08
 Moshiri
 Business

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