# Data Handling

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Statistics is a branch of mathematics, which studies how to collect, organize, analyze, interpret and present data.

Data is the collection of information in the form of numbers, and any information in its original form is called raw data. It is of two types: Qualitative (that describes the quality or characteristics of the given information) and Quantitative (that describes the quantity of the given information).

Organisation of Data means to collect the proper information from the data and arranging the data in proper format to make it more meaningful.

The representation of data in the form of a table is called Tabulation of data. This includes the observation and frequency. Frequency table is formed with the help of Tally Marks method. In this method, each frequency is represented by a line and after every fourth line, the fifth line crossing the four lines is drawn.

A pictograph represents the data through the pictures of the objects. It helps in answering the questions based on the data at a glance. The picture symbols used represents certain number of items or things. These symbols are called keys.

While constructing pictographs,
The pictorial symbol should be self-explanatory, concise and clear.
The change in numbers must be represented by an increase or a decrease in the number of symbols and not by the size of the symbols.
It should be easy to understand and convey information.
Bars of uniform width can be drawn horizontally or vertically with equal spacing between them and then the length of each bar represents the given number. Such method of representing data is called a Bar diagram or a Bar graph.

To construct a bar graph:
Draw two mutually perpendicular lines on the plane of the paper.
If the bars are drawn vertically, then the scale of the heights of the bars is shown along the vertical axis.

The width of the bar and the gap between the bars should be uniform.

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