GAURAVSAMPLEDESIGN

8/7/2019 GAURAVSAMPLEDESIGN

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SUBMITTED BY:

GAURAV SINGLA

0903271

3ME6

SUBMITTED TO:

Lect. Luxmi Shankar


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SAMPLE:

When we select a few out of the total population , it is called a sample .

PURPOSE OF SAMPLING:

The basic idea of sampling is that by selecting some of the elements in

population, we may draw conclusions about the entire population


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Why Sample should be taken?

To minimise the total cost Greater accuracy of results

Greater speed of data collection

Availability of Population elements.

What is Good Sample?

Howwell it represents the characteristics of the population itpurports to represent

In measurement terms, the sample must be valid. Validity of a sample depends on two considerations :

Accuracy

Precision


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Accuracy :1. Degree towhich bias is absent from the sample.

2. Some sample elements underestimate the population values being studied and other

overestimate them.

How do Bring in Accuracy?Under-estimation and over-estimation offset each other and gives a sample value that is

generally close to the population value.

Offsetting requires large numberof elements

Precision:1. No sample will fully represent its population in all respects

2. Differences in the sample and population values occurs due to random fluctuationsinherent in the sampling process.

3. This is called sampling error and reflects the influences of chance in drawing thesample members.


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` It saves time and money.

` Produces faster results.

` If the population is homogenous, sampling also produces

sufficiently accurate results.

` In case the population is infinite, sampling is the best method.


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` Sample should be representative of the population from

it is selected. It should be applicable to the whole

population.

` It should reduce the bias.

` It should be able to deliver complete information about

the study.

` It should be large enough to take advantage of reliability

etc.

` It should be small enough to handle , to cost low andfinish in the stipulated time.


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` Identify the population.

` Determine the sampling unit.

` Preparation of sampling frame (it is the list of all

identified sampling units surely but only once).` Determine the sampling method to be used for

selecting the sample.

` Determine the sample size.

` Select the sample.


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Identifying the population(universe):

The first step in developing any sample design is to clearly define the set of

objectives technically called universe , to be studied.

The universe can be finite or infinite

Inf

inite universe the numberof

items is certain, but in caseof

an inf

inite universethe numberof items is infinite i.e we cant have any idea about the total numberof

items.

Example:

The population of a city, the number of workers in a factory and the like are

examples of finite universes

The numberof stars in the sky. Listeners of a specific radio programme, throwing

a dice etc are example of infinite universe.

STEP 1


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Sampling unit:

A decision has to be taken concerning a sampling unit before selecting

sample.

Sample unit may be a geographical one such as state, district, village,

etc or a construction unit as house, flat, etc, or it may be social unit

such as family, club, school, etc,or it may an individual.

STEP 2


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SAMPLING FRAME:It is also known as source list from which sample is to be drawn.

It contains the names of all items of a universe (in case offinite universe

only)

If source list is not available, researcher has to prepare it and it should be

correct, reliable, and appropriate.

STEP 3


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Sampling Techniques

Probability Sampling Non- Probability Sampling

1. Simple Random Sampling

2. Systematic Sampling.

3. Stratified Random

Sampling4. Cluster Sampling

5. Area Sampling

6. Multistage Sampling

Convenience Sampling

Judgment Sampling

Quota Sampling.

STEP 4


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` Size ofsample:

Refers to the no of items to be selected from the universe to constitute a sample.

The size of the sample should neither be excessively large nor too small, it should be optimum.

` Duration Of study.

` Depth of the study

` Characteristics of Population.

` Technique of Sampling used.

` Precision and confidence level Required

` Analysis Needs :If data analysis is going to be complex, we require smaller sample size.` Availability of Resources.

STEP 5


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Sampling procedure:

Finally, the researcher must decide the type of smple he will use i.e hemust decide about the technique to be used in selecting the items for

the sample.

Obviously, he must select that design which, for a given sample size

and for a given cost, has a smaller sampling error.

STEP 6


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Errors to be avoided

1. Inappropriate sampling frame

2. Defective measuring device3. Non-respondents

4. Natural bias in the reporting of data

GAURAVSAMPLEDESIGN

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