Transcript
Refers to those methods which are used for making judgments and taking actions based on sample(taken from population).POPULATION: The larger group of items having common measurable characteristics.SAMPLE: The limited number of items selected from the larger group which itself represents the whole population.NEED: It saves time , money and energy.
BASIC SAMPLING DESIGN TYPES
RANDOM/ PROBABILITY SAMPLING: Every unit has equal chance to be selected in sample.
NON RANDOM / NON PROBABILITY SAMPLING: Every unit has no equal chance to be selected in sample.
METHODS
Each and every unit in the population has an equal and independent chance of being included in the sample .
The method of selection is specified , objective and replicable.
Types:Simple random sampling with replacementSimple random sampling without
replacement.
SIMPLE RANDOM SAMPLING
MERITS: DEMERITS:Easy to use. Requires up- to
date & complete list of population.Eliminate personal Time consuming & biasedness. costly in case of scattered
information.
STRATIFIED RANDOM SAMPLING
It is used when population is heterogeneous in nature .
Techniques of stratification(division into different layers or groups) is used.
Methods of allocation of sample size:Proportional allocation Equal allocation
MERITS:
It gives more representative sample in case of heterogeneous sample.Improves sampling design & brings administrative convenience.
DEMERITS:
Result will be biased in case of faulty stratification.
Difficult to classify in case of small size of population.
SYSTEMATIC SAMPLING
In this type of sampling only the first sample unit is selected at random and the remaining units are automatically selected in a definite sequence at equal spacing from one another.
MERITS: DEMERITS:
Easy to operate and checking Complete and accurate list of sample is needed. Save time and labour Relative efficiency depends upon properties of population.
It is used when area is very big. The area is divided in to small overlapping or neighboring areas called CLUSTER.
CLUSTER SAMPLING
MERITS :
More economical and easy to operate
DEMERITS:
Less efficient.
First selecting the clusters and then selecting only some elements of the selected clusters.
MULTI-STAGE SAMPLING
MERITS:More flexible as compared to other methods of
sampling.Different sampling techniques can be used at
different stages.DEMERITS:Errors are likely to be greater due to variability
of the estimates .
Based on hand picking of the individual elements.
Selection is done by choice not by chance .MERITS: Useful information can be obtained .DEMERITS:Influenced by personal biasness.
NON- RANDOM /NON –PROBABILITY SAMPLING:
Purposive / judgment sampling
Consist of simply taking the cases that are available.
MERITS:Convenient to useDEMERITS:Personal biasness.
CONVENIENCE SAMPLING
Used when population size is large and abundant.Used to improve representativeness of the study.LOGIC:Certain relevant characteristics describe the
dimensions of the whole population.MERITS:Used in surveys particularly in the commercial
world .Used to reduce the cost of surveys.DEMERITS:Biasness is there.
QUOTA SAMPLING
Special type of non probability sampling where respondents are difficult to identify thus best located through referral network.
MERITS :Reduced sample size and cost .DEMERITS:Biasness is likely to enter.
SNOWBALL (Network or chain) SAMPLING
SPEEDECONOMYADAPTABILITYSCIENTIFIC APPROACHLEADS TO GOOD RESULTS
ADVANTAGES OF SAMPLING
TECHNIQUES:
Various sampling techniques adopted for investigation usually offers great advantages as to cost, time & sometime even to quality of results .
Simple random & purposive sampling techniques are mostly used at M.Sc. & PhD level.
Multistage sampling and stratified sampling should be used to get proper representation of population.
CONCLUSION:
Research Methodology by C.R.KothariResearch Methods by John Adams/Hafiz
T.A.KhanResearch for marketing decision by Paul.
E.Green.Marketing management by Arun Kumar.
REFERENCES:
POSTIVE CRITISISM AND SUGESTIONS ARE WELCOME
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