Post on 12-Jun-2015
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NOTE --The purpose of collection of data is to show
evidence for reaching a sound and clear solution to an economic problem.
Statistical enquiry :-it means a search conducted by using statistical methods.
Or we can say that statistical enquiry means statistical investigation.
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The person who conducts this investigation is called
an investigator.
The investigator needs help of enumerator( who collect information).
And respondents( who provide the information) for statistical enquiry.
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Sources of Data
External Data
Primary Sources
Secondary
Sources
Internal Data
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Internal sources of Datao Definition – information created by the operation of
an organization that include sale, profit etc.
o Different organisations and government.
o Internal data may be available in the organisation about sale, production, interest etc
o Such data are compiled and used for future planning.
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External sources of Data Definition – External sources refer to that data
collected from outside the organization
Information collected from outside organisations and institutions is called external data.
External data can be obtained by primary and secondary sources.
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Primary sources Meaning- data collected by the investigator for his own
purpose , for the first time , from beginning to end , are called primary data.
Methods of collection of primary Data
1.Direct personal investigation
2.Indirect oral investigation
3.Information from local sources
4.Information through filling questionnaires and schedules –
(a)Mailing method
(b)Numerator`s Method
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Secondary Data –These are those which are already in existence. Its also known as second hand data.
Published Sources Unpublished Sources
a. Government publication
b. Publications of internal bodies
c. Semi-official publication
d. Report of committees and commission
e. Private publication
1. Journals and News paper
2.Research Institutions
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Census and Sampling investigation Census Method – when a statistical investigation
is conducted wherein , the data is collected from each and every element of the population , it is known as census method.
1. This method is generally adopted when area of investigation is limited.
2. High trained investigators are needed to maintain a high degree of accuracy.
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Merits and Demerits of Census MethodMerits : Intensive study of population
High degree of accuracy and reliability
Suitability of the method
Demerits :
Expensive
Need more time and manpower
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Meaning of Sampling Method Sampling method : When only some representative
items of a population are selected and data collected from these items are used for the analysis, the method is known as sampling method
Factors Affecting Size of sample
1. Size of Population
2. Degree of Accuracy Desired
3. Homogeneity of heterogeneity of the population
4. Nature of the study
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Merits of Sampling Method Reduced Cost
Greater speed
Greater accuracy
Administrative convenience
Detailed Enquiry
Greater Scope
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Demerits of Sampling Method Difficulty to achieve cent percent accuracy
Lack of representativeness of sample
Lack of specific or specialized knowledege
Bias in the selection of sample
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Types of sampling Random sampling
Purposive sampling
Systematic sampling
Quota sampling
Random sampling
Purposive sampling
Systematic sampling
Quota sampling
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Random SamplingMeaning :-Method in which each and every item of the
universe has an equal chance of being selected in the sample is called Random sampling.
Like as lottery method
Merits: 1) Free from bias
2) Equality
3) Representative of the population
Demerits: 1)Ignores important items
2) No proportionate representative
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Purposive sampling Method in which the investigator himself collect or
chooses the samples from the universe, which in his opinion are the best representatives of the population is purposive or deliberate sampling.
Merits :- 1) Flexible
2) Facilitates purpose of study.
3) Simple
Demerits :- 1) Biased
2) Not reliable
3) Inaccurate
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Systematic Sampling Method in which items of the universe are arranged
numerically , alphabetically and geographically and every nth items of the numbered items is selected as a sample items is called systematic sampling.
Merits :- 1) Simple
2) Not Biased
3) Less time consuming
4) Satisfactory conclusions
Demerits :- 1) Unfair
2) Unsuitable if items are homogeneous
3) Unsuitable if size of universe is large
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Quota sampling Meaning – Method in which population is divided into
different groups or classes according to different characteristics of the population, is called Quota sampling.
Merits :- 1) Economical
2) Reliable
Demerits :- 1) Personal bias
2) Impossible to detect sample error.
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Statistical Errors In the statistical terms, the difference between the
collected data and actual value of facts is termed as statistical errors.
In other words , the difference between estimated value and the actual value is called statistical error.
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