Quick Revision Notes

Class 11 Economics: Presentation of Data

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1. Introduction

Presentation of data refers to the exhibition of collected and classified data in a clear, attractive, and easily understandable form so that it can be readily analyzed and interpreted.

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2. Modes of Presentation of Data

Data can be presented mainly in three ways:

1. Textual Presentation (वर्णनात्मक प्रस्तुतीकरण): Data is presented in the form of text/sentences. Useful when the quantity of data is small.
2. Tabular Presentation (सारणीयन प्रस्तुतीकरण): Data is organized in rows and columns.
3. Diagrammatic and Graphical Presentation (आरेखीय और ग्राफिकल प्रस्तुतीकरण): Data is presented using geometric figures (bars, circles), lines, and curves.

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3. Tabular Presentation (Tabulation)

Tabulation is the systematic and logical arrangement of classified data in rows and columns.

Essential Parts of a Good Table:

1. Table Number: For identification.
2. Title: Brief description of the contents of the table.
3. Headnotes: Additional information given below the title (e.g., units of measurement).
4. Stubs: Titles of the rows (left-hand side).
5. Captions: Titles of the columns (top).
6. Body of the Table: The actual numerical data/figures placed in cells.
7. Unit of Measurement: Units used for data (e.g., in kg, in rupees).
8. Source: Origin of the data (from where data was collected).
9. Footnotes: Clarification of any specific item in the table.

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4. Diagrammatic Presentation of Data

Diagrams make data more attractive and easier to comprehend. The major types are:

A. Geometric Diagrams

• Bar Diagrams (दंड आरेख): Made up of simple bars of equal width. Lengths/heights of bars represent the magnitude of data.
  • Simple Bar Diagram: Represents a single set of numerical data.
  • Multiple Bar Diagram: Used to compare two or more sets of data (e.g., imports and exports over years).
  • Sub-divided (Component) Bar Diagram: Bars are divided into various segments representing different components of a total.
• Pie Diagram (पाई आरेख / वृत्ताचित्र): A circle divided into sectors whose areas are proportional to the values they represent.
  • Formula for Pie Chart Angle: Angle of Sector = (Component Value / Total Value) × 360°

B. Frequency Diagrams

Used to present grouped frequency distributions.

• Histogram (आयताचित्र): A two-dimensional diagram of continuous frequency distribution consisting of adjacent rectangles erected on the class intervals.
  • Note: Mode can be located graphically using a histogram.
• Frequency Polygon (आवृत्ति बहुभुज): Formed by joining the mid-points of the tops of the rectangles in a histogram (or by plotting mid-points against frequencies and joining them with straight lines).
• Frequency Curve (आवृत्ति वक्र): Smoothed version of a frequency polygon, drawn freehand.

C. Arithmetic Line Graphs (Time Series Graphs)

• A graph showing changes in values of a variable over a period of time (e.g., population growth, GDP over 10 years).
• Time (X-axis) vs Variable (Y-axis).

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5. Rules for Constructing Diagrams and Graphs

• Neatness and Cleanliness: Should be visually appealing.
• Appropriate Scale: Scale must be properly chosen to fit the data accurately.
• Index / Legend: Proper shading, colors, or indices must be explained clearly.
• Source Note: Always mention the source at the bottom.
• Simplicity: Avoid overcrowding with too much information in a single diagram.

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6. Quick Distinction: Table vs. Diagram

Feature	Tabulation	Diagrammatic Presentation
Nature	Contains exact numerical figures.	Gives visual approximation and general trends.
Usefulness	Best for detailed and reference work.	Best for quick understanding and comparison.
Analysis	Facilitates deep statistical analysis.	Limited scope for further statistical calculation.