Date :
Data is the collection of information or facts. It may be a collection of numbers, figures, words or symbols.
Raw Data :
The data that has been collected in the original form is called raw data.
For example :
The marks obtained by 50 students in the Social Studies exam are 60, 40, 35, 27, 67, 72, 40, 37, 45, 50, 52 and so on up to 50 items.
This collection of data is raw data.
Observation :
Each of the items in the raw data is called an observation. The marks of each student stands for an observation in the raw data.
Type of Data :
· There are two types of data — primary data and secondary data.
· Primary data is the data collected directly from the source.
· Secondary data is the data collected from secondary sources such as the internet, TV, libraries, 
   newspapers. etc
For example :
Mr Sen asks the students to give their choice for the particular location they would like to go, the games they would like to play, the type of food they would like to have on their trip, he is getting the information directly from the source. This is primary data collection. When he is collecting information about weather, or accommodation facilities. he may collect these from the internet, travel brochures, newspapers, magazines, television and other souces. These sources are secondary sources is called secondary data.
Organisation of Data :
To draw a meaningful conclusion from the data, the data must be organized. Understanding and analyzing the data becomes easier when it is represented by pictures or tables.
Tabular form :
Consider the data given here 75%, 88%, Devan, Charu, Sajita, Arvind, 70%, 60%, 83%, 90%, 94%, Greg, Manisha, Vijayan, Ahmed, Raghu, Neetu, 66%, 77%, 72%. This is raw data.
The data given above are facts in words and figures. Unless the available data is property presented, we cannot get meaningful information from it. Given below is a tabular representation of the above data. This makes the information easy to understand.
 Frequency distribution :
Let us study the peak hour traffic at a road junction to share it with the town or city addministrators to help them develop that junction for easy traffic flow. We need to collect the data about the number of trucks, cars, other motor vehicles, and cycles passing through that junction during a fixed period at the peak hour.
We will try to find the number of vehicles passing through that junction during the peak interval of 9.00 a.m. to 9.30 a.m.
For this you have to prepare a data collection sheet.
You find here two new words tally and frequency. Tally is a mark 'l' we put in the chart against each item. For example, if a car passes the junction, we mark one tally 'l' in the box against car. When four cars have passed, the tally will look like this "llll'. When the fifth car passes, we do not write 'lllll' but we put a cross across the four tallies like . This forms a group of 5. Similarly
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