Here we will learn the following concepts in detail:
- A brief introduction to statistics
- Definition of statistics
- What is data
- How many types of data
- Methods of collection of data
- Difference between primary data and secondary data
- Representation of data
Introduction to Statistics
In ancient times also statistics were used at that time in India here are some incidents that are proof that at that time statistics also have its importance like
1. In Mahabharatkal during Damayanti’s swaybar Going with king Nal, King Rituparna calculated the exact number of fruits and leaves on the tree based on the sample of a tree.
2. In Chandragupta Maurya’s reign (324-300 BC), the description of registration of birth-death and the arrangement of governance on its basis is found in Kautilya’s Arthashastra.
Many examples of the use of statistics are found in wartime, in the arrangement of government, and even in daily life, when we see in newspapers, electronic media, many channels, magazines, and other communication tools, information about the temperature of the cities, the situation of rainfall from place to place, etc. Factual and comparative information is obtained through data.
We use this data in some way or another throughout our daily lives. so it is necessary for us that get the necessary information from these data.
Definition of Statistics
It is the process of collecting the data, organizing that data, analysis of the data, interpreting of data, and at last, extracting meaningful information from that data.
The statistics word has taken from the Latin word status, the meaning of status is ‘ a (political) state ‘.
What is Data
The collection of facts and information in numerical form in statistics is called data.
On the behalf of collection data, there are two types of data.
Primary Data
When the information (data) is collected by the investigator himself or herself with a definite objective in his or her mind, the data obtained is called primary data
example for in your school the collection of heights of 20 students in your class.
primary data are reliable and relevant because they are original in character and are collected by the investigator himself
Method of Collection of Primary Data
We can collect the primary data in the following manner :
- by Interview: here telephonic or face to face
- by questionnaire
- by observation
Secondary Data
the data (information )which is not originally collected rather than gathered from a source that already had the information stored in this manner the collection of data is called secondary data.
example in your school collect the number of absentees each day in your class for a month, how you will collect this data I am sure by your class attendance register which is already a source of some information
this is most important that the source is reliable by which we are collecting the data, here is the great care required
Method of Collection of Secondary
As we know that secondary data is not collected by the original investigator, here are two types of sources by which we will collect the secondary data
1. Published Sources
- U.N.O.
- Government Publications
- Public Records
- Historical and Statical Documents
- Business Documents
- News Papers
- Semi-Government Publications etc.
2. Unpublished Sources
- Unpublished Biographies
- Diaries
- Unpublished Letters etc.
Difference between Primary and Secondary Data
1. Primary data is collected by the researcher but secondary data is not collected by the researcher himself.
2. Primary data is the most accurate but secondary data is less accurate as compared to primary data.
3. Primary data is organized data in a proper manner but secondary data as you know is gathered by other sources that’s why it is not in a properly organized form.
4. For A collection of primary data required large human resources, more time, and is also expensive but for collection of secondary data is very easy because it is collected by already available sources hence secondary data collection is less expensive.
Representation of Data
As soon as work related to the collection of primary and secondary data is over, the investigator has to find ways to present both types of data in a form that contains the following key points
- The first one is meaningful,
- The second point is easy to understand.
- And the last point fulfills its main features with a brief look.
Now take some examples to represent the data
Example 1: Following data are the marks obtained by 10 students on the English test as given below :
55 25 36 95 73 60 42 63 78 76
The data in this form is called raw data.
by looking at this form if we are going to find the lowest and highest marks then we take some time to search for that one
but if this score is arranged in ascending or descending order
25 36 42 55 60 63 73 76 78 95
now we can clearly see the lowest marks are 25 and the highest marks are 95.
Range
The difference between the highest and the lowest value of given data is called the range.
now the range, in this case, is 95 -25 =70
Presentation of data in ascending and descending order can be quite a time taking if the number of observations in an experiment is large as in the case of the following example:
Example 2: Consider the marks obtained (out of 100 marks )by 30 students of Class IX of your school :
10 20 36 92 95 40 50 56 60 70
92 88 80 70 72 70 36 40 36 40
92 40 50 50 56 60 70 60 60 88
here we will make a frequency distribution table:
| Marks | Tally marks | number of students
(i.e., the frequency ) |
| 10
20 36 40 50 56 60 70 72 80 88 92 95 |
I
I III IIII III II IIII IIII I I II III I |
1
1 3 4 3 2 4 4 1 1 2 3 1 |
| Total | 30 |
This table is called an ungrouped frequency distribution table.
If the data is very large then we will use grouped frequency distribution table.
| Class interval | Frequency |
| 10 -20
20 -30 30 -40 40 -50 50 -60 60 -70 70 -80 80 -90 90 -100 total |
1
1 3 4 5 4 5 3 4 30 |