Introduction and Basic concepts of Statistics
Meaning and Definition of Statistics
Meaning of Statistics
The word Statistics is usually used in two senses. They are -
In plural form, it stands for numerical facts (facts expressed in numbers) pertaining to a collection of objects, a situation or a phenomenon. Thus, Statistics' relating to the strength of a college are "The strength of the college is 2,500 of which 800 are girls. 1500 students inclusive of 500 girls, study in degree classes".
In singular form, it stands for the science of collection, organization, analysis and interpretation of numerical facts or data.
Definition of Statistics
Prof. Horace Secrist defines Statistics as follows.
"By Statistics we mean, aggregate of facts affected to a marked extent by multiplicity of causes, numerically expressed, enumerated or estimated according to reasonable standards of accuracy, collected in a systematic manner for a pre-determined purpose and placed in relation to each other."
Characteristics of Statistics
According to Prof. Horace Secrist, the following characteristics of Statistics can be noticed.
1. Statistics means an aggregate of facts.
Facts can be analysed only when there are more than one fact. Single fact cannot be analysed. Thus, the fact 'Mr. Been is 180 cm tall", cannot be statistically analysed. On the other hand, if we know the heights of 40 students of a class, we can comment upon the average height, variation, etc. Hence, only a collection of many facts can be called Statistics.
2. Statistics are affected to a marked extent by multiplicity of causes.
The facts are the results of action and interaction of a number of factors. Thus, the statistics of yield of paddy is the result of factors such as fertility of soil, amount of rainfall, quality of seed used, quality and quantity of fertilizer used, etc. These factors, in tum, are the results of many other factors.
3. Statistics are numerically expressed.
Only numerical facts can be statistically analysed. Therefore, facts such as 'Price decreases with increasing production' cannot be called statistics.
4. Statistics are enumerated or estimated according to reasonable standards of accuracy.
The facts should be enumerated (collected from the field) or estimated (computed) with required degree of accuracy. The degree of accuracy differs from purpose to purpose. In measuring the length of screws, an accuracy up to a millimeter may be required, whereas, while measuring the heights of students in a class, accuracy up to a centimeter is enough.
5. Statistics are collected in a systematic manner.
The facts should be collected according to planned and scientific methods. Otherwise, they are likely to be wrong and misleading.
6. Statistics are collected for a pre determined purpose.
There must be a definite purpose for collecting facts Otherwise, the facts become useless and hence, they cannot be called statistics.
7. Statistics are placed in relation to each other.
The facts must be placed in such a way that a comparative and analytical study becomes possible. Thus, only related facts which are arranged in logical order can be called statistics.
Arithmetic Mean (Mean)
Arithmetic mean of a set of values is obtained by dividing the sum of the values by the number of values in the set. Its value is obtained by adding together all the items and by dividing this total by the number of items.
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Redrafted for Educational Purpose.
Book Reference:
1. Business Statistics by S P Gupta and M P Gupta
2. Elementary Statistical methods by S P Gupta
3. Business Statistics by Raj Mohan
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