stats- sampling scope & limitation

8/2/2019 Stats- Sampling Scope & Limitation

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Scope, Importance and limitation ofStatistics & Sampling

Presented by:Avyudaya Pratap Singh

Chandan kumar

Swapnil Bhongade


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Application of Statistics Statistics & Government

Statistics help in framing suitable fiscal and monitoring polices to

government. Example- Statistics helps in all the govt. department such

as transport, finances, defence, railways, telegraph, agriculture, etc.

Transport- Number of buses require in a city planned on the basis of

existing buses and number of people using public transport.

Statistics & Business

Statistical methods are used to solve many business problem.

Example- Marketing researcher uses consumer buying habit to

develop a new product.

Production managers look quality control data to decide what

adjustment should make for the manufacturing .

Statistical table and charts are used by sales manager to represent anumerical facts of sales.


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Application of Statisticscontd.. Statistics & Economics

Statistical data and statistical methods are of immense help in the properof understanding of economic problem and in the formulation ofeconomic policy. Example- What to produce, How to produce and For

whom to produce? These question needs lot of statistical data in theabsence of which it is not possible to arrive at the correct decision.

Statistical data help in understanding supply and demand of goods.

Example- Gross national product, fluctuation in stock market, etc.

Statistics & science

Statistical techniques have proved extremely useful in the study of allnatural sciences like astrology, biology, medicine, botany, etc. Example-Diagnosis of disease can be done by doctor on basis of statistical data ofbody temperature, BP, pulse rate, etc.

Botany- Study of plant growth on the basis of statistical data oftemperature, soil fertility, etc.


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Limitations Statistics does not deal with individual

measurement.

It deals with the aggregate facts, the study of individualmeasurement lies outside the scope of statistics.

Example- Wage on by an individual worker at any one time takenby itself is not a statistical datum. But the wages of workers of afactory can be used statistically.

Marks of students, Height of students.

Statistics deal with quantitative characteristics.

Statistics are numerical statement of facts.

Qualitative characteristics such as honesty, efficiency can not beexpressed. Example- Study of intelligence of boys in a class isexpressed on the basis of mark obtained in examination.


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Limitations Statisticals results are true only on an avrage.

The conclusion obtain statistically are not universally true, they are

true only under certain condition.

Statistics is only one method of studying a problem.Statistical tool do not provide the best solution under all

circumstances. Hence, it is necessary that statistical conclusions

should be supplemented by other evidences.

Statistics can be misused.

Statistics are like the clay, they can be molded in the manner so as to

established right or wrong conclusion.


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SamplingSampling is simply the process of learning

about the population on the basis of sample

drawn from it.

Process of sampling involves three elements.

1. Selecting the sample.

2. Collecting the information.3. Making the inference about the population.


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Laws of Sampling There are two important laws on which theory of

sampling is based.

1. Law of statistical Regularity.

It states that a moderately large number of itemchosen at random from the large group arealmost sure on the average to possess thecharacteristics of the large group.

2. Law of Inertia of large numbers.

It states that other things being equal, large thesize of sample more accurate the results arelikely to be.


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Methods of samplingSampling method

Non probability Probability1. Judgement 1. Restricted

2. Quota A. Stratified

3. Convenience B. SystamaticC. Cluster

2. Unrestricted


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Methods of sampling contd..Judgment Sampling- In this method choice of

sample item depends exclusively on thejudgment of investigator. Ex- If ten students

each to be selected from a class of sixty foranalyzing the study habits of students,investigator would select 10 students in hisopinion are representative of the class.

Quota Sampling- In a quota sampling, quotasare setup according to some specifiedcharacteristics such as age, income, etc.


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Methods of sampling contd..Convenience Sampling- Convenience sampling

is obtained by selecting convenient population

unit. It is also called as Chunk. Which refers to

that fraction of the population is been

investigated which is selected neither by

judgment nor by probability but by

convenience.


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Restricted sampling-Stratified sampling: can be used whenever thepopulation can be partitioned into smaller sub-

populations, each of which is homogeneous accordingto the particular characteristic of interest.

Cluster sampling: can be used whenever thepopulation is homogeneous but can be partitioned. Inmany applications the partitioning is a result ofphysical distance. For instance, in the insuranceindustry, there are small"clusters" of employees infield offices scattered about the country. In such acase, a random sampling of employee work habitsmight not required travel to many of the"clusters" or

field offices in order to get the data. Totally samplingeach one of a small number of clusters chosen atrandom can eliminate much of the cost associatedwith the data requirements of management


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Methods of sampling contd..Systematic sample is formed by selecting 1 unit at

random and then selecting a additional units at evenlyspaced intervals until the sample has been formed.

K= N/n

N= Universal size, n= Sample size, K = Samplinginterval

Ex- 96 students with roll num from 1 to 96. It isdesire to take the sample of 10 students using

systematic sampling methods sampling sizeK= N/n

K=96/10 =9.6

4,14,24,34,44,54,64,74,84,94.


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Methods of sampling contd..Unrestricted Random Sampling refers to that

sampling techniques, In which each and every

unit of population has an equal opportunity of

being selected in the sample.


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stats- sampling scope & limitation

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