Statistics introduction(basics)

Fundamentals of statestics

The word statistics is derived from modern latin. It has different names in different languages and countries. They are

  • Status - latin
  • Statista - Italian
  • Statitix - Germen
  • Statistique - French

Usage

Statistics is can be used in Economics, Accounts, Management etc..

Prof. Prasanta Chandra Mahalanobis is also known as the father of Indian Statistics. 

Statestics may be defined as "science which deals with the collection, analysis and interpretation of numerical data".

Statestics have two different senses. 

  • In singular sense, the scientific method that is employed for collecting, presenting and analysing data, finally leading to drawing statistical conclusion about some important characteristics of the data. 
  • In plural sense, it is a quantitative or qualitative data that are usually collected with a view of analysis. Ex:- production of rice in india.
Data means information collected through different sources. This data is 2 types, primary data( data collected directly by seeing or experiencing), secondary data( data collected from enquiring another person who experienced or saw directly, data from magazines,newspapers). 

This data which is collected is presented before us in different forms.
  1. Individual series
  2. Descrete series(simple frequency distribution)
  3. Continuous series (Grouped frequency Distribution).

Individual series

This is very simple presentation
Ex:- 1. Marks secured by 15 students in a class are 30,30,30,35,35,40,40,40,40,37,37,32,27,48,48.
Ex:- 2. Wages of 10 workers in a factory are 8000,8000,7000,8500,7000,7600,9000,9000,8500 8000.
Ex:- 3. A cricketer scored 16,45,89 in 3 matches.

These are all in the form of individual series. Every number is individually given, that number is not dependent on any other number or factor for its indentity.

Descrete series

This is represented using table.
The same examples of individual series are taken here.

Ex:-1. _______x_______|______f(x)______
                    30              |            3
                    35              |           2
                    40              |           4
                    37              |           2
                    32              |.          1
                    27              |           1
                    48              |           2 
          ___________________________________
In this table x means marks obtained.
F(x) means frequency of marks.
The meaning of first line  in table means 30 repeated 3 times
35 repeated 2 times
40 repeated 4 times 
37 repeated 2 times
32 repeated 1 time
27 repeated 1 time
48 repeated 2 times 
We just changed the format of data. The matter given is same in both. 30 repeated 3 times means 30 marks obtained by 3 students. Remaining data also same to this.

Continuous series

Again the same example will be given here in the form of continuous series form.
Ex:- 1. Marks secured by 15 students in a class are 30,30,30,35,35,40,40,40,40,37,37,32,27,48,48.
_______x_______|______f(x)______
       25-30           |          4
       31 -35          |          3
       36-40           |          6
       41-45           |          0
       46-50           |          2  ______________________________

Here the fist line means 
  • No. Of students who Obtained marks from 25 to 30 (27,27,30,30,30)
  • Totally 6 students obtained marks that lie between and including 30 to 35(32,35,35)
  • Totally 6 students obtained marks the lie from 36 and 40(37,37,40,40,40,40)
  • Totally 2 students obtained marks from 46-50(48,48).
1) Every line in this table is called class.
2) Here you saw a class 25-30 in table. This 25 is called as lower limit and 30 is called as upper limit. 
2) The difference between lower limit and upper limit is called class length. Here the class lenth for 25-30 class is 30 minus 25 is 5(30-25=5). So 5 is the class length.

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