1.What is diagram?
A diagram is a visual form for presentation of statistical data, highlighting their basic facts and relationship.
2.What are the significance of diagrams?
Diagrams and graphs are extremely useful because of the following reasons.

• They are attractive and impressive.
• They make data simple and intelligible.
• They make comparison possible
• They save time and labour.
•  They have universal utility.
• They give more information.
•  They have a great memorizing effect.

3.What are the rules for making a diagram?

•  A diagram should be neatly drawn and attractive.
•  The measurements of geometrical figures used in diagram should be accurate and proportional.
•  The size of the diagrams should match the size of the paper.
•  Every diagram must have a suitable but short heading.
•  The scale should be mentioned in the diagram.
• Diagrams should be neatly as well as accurately drawn with the help of drawing instruments.
•  Index must be given for identification so that the reader can easily make out the meaning of the diagram.
•  Footnote must be given at the bottom of the diagram.
•  Economy in cost and energy should be exercised in drawing diagram.

4.What are the various types of diagrams?

•  One-dimensional diagrams
•  Two-dimensional diagrams
•  Three-dimensional diagrams
•  Pictograms and Cartograms

5.Write short notes on Simple Bar diagram.
Simple bar diagram can be drawn either on horizontal or vertical base, but bars on horizontal base more common. Bars must be uniform width and intervening space between bars must be equal.While constructing a simple bar diagram, the scale is determined on the basis of the highest value in the series. To make the diagram attractive, the bars can be coloured. Bar diagram are used in business and economics.
6.What is a pie diagram?
A pie chart is a circular chart divided into sectors, illustrating relative magnitudes or frequencies. In a pie chart, the area of each sector is proportional to the quantity it represents. Together, the sectors create a full circle. In constructing a pie diagram the first step is to prepare the data so that various components values can be transposed into corresponding degrees on the circle. The second step is to draw a circle of appropriate size with a compass. The size of the radius depends upon the available space and other factors of presentation. The third step is to measure points on the circle and representing the size of each sector with the help of a protractor
7.What is Lorenz curve? Mention its important.
Lorenz curve is a graphical method of studying dispersion. It was introduced by Max.O.Lorenz, a great Economist and a statistician, to study the distribution of wealth and income. It is also used to study the variability in the distribution of profits, wages, revenue, etc. It is specially used to study the degree of inequality in the distribution of income and wealth between countries or between different periods. It is a percentage of cumulative values of one variable in combined with the percentage of cumulative values in other variable and then Lorenz curve is drawn.
8.Write short note on Histogram.
A histogram is a bar chart or graph showing the frequency of occurrence of each value of the variable being analysed. In histogram, data are plotted as a series of rectangles. Class intervals are shown on the ‘ X-axis’ and the frequencies on the ‘ Y-axis’ .
9. What is meant by an Ogive?
Ogive or Cumulative frequency curve is the curve which is constructed by plotting frequency data on the graph paper, in the form of smooths curve.
10. What is a multiple bar diagram ?
Multiple bar diagrams are those diagrams which show two or more sets of data simultaneously.