Diagram

Diagrammatic Representation of Data

I

n order to make the data suitable for analysis and

interpretation, the after classification and tabulation, the have to be presented properly by using Charts and Diagrams, so that the salient characteristics of the data which is crucial in terms of decision making and adoption of new policies, comes out.

A

dvantages:-

Diagrams are appealing to the eyes as well as to intellect, and are therefore helpful is assimilating the data readily and quickly. It helps to find out the relative position of different sub divisions and can draw a meaningful inference on the basis of this comparative analysis. Moreover a chart or diagram can clarify a complex problem and reveal facts, which are not apparent from the tabular form. It is sometimes necessary in finding the trend in the time series.

Bar Diagram

Bar diagram consists of a group of equispaced rectangular bars, one for each category (or class) of given statistical data. The bars are starting from common base line, must be of equal width and their length represents the value of the statistical data.

Types of Bar Diagram

Bar diagrams are of following types:1) Simple bar diagram 2) Subdivided (or component) bar diagram 3) Multiple bar diagram 4) Percentage bar diagram 5) Deviation bar diagram

1) Simple bar diagram

Simple bar diagrams are very popular in

practice, they can present only one category of data.

For example:- while presenting the total

number of worker for the last few dacades,one can only depict the total number of worker in the simple bar diagrams not its sector wise (agricultural or nonagricultural) distribution.

Table 1 :- Total number of worker in India (1860-1950) Year

Number of worker(Million)

1860

10.5

1870

13.0

1880

17.4

1890

23.3

1900

29.1

1910

37.0

1920

42.4

1930

48.9

1940

51.7

1950

59

2)Subdivided (or component) bar diagram

These subdivided bar diagrams are used to present various parts of the total.

For Example:-The sector wise (agricultural or non-agricultural) distribution of total worker may be represented by a subdivided bar diagram.

Title:-Distribution of total workers in agricultural and non-agricultural sector for the years 1860-1950 Year

Agricultural Worker(Million)

Non-Agricultural Worker(Million)

Total Number of worker(Million)

1860

6.2

4.3

10.5

1870

6.9

6.1

13.0

1880

8.6

8.8

17.4

1890

9.9

13.4

23.3

1900

10.9

18.2

29.1

1910

11.6

25.4

37.0

1920

11.4

31.0

42.4

1930

10.5

38.4

48.9

1940

8.8

42.9

51.7

1950

6.8

52.2

59

Bar charts of agricultural worker

Bar charts of non-agricultural worker

70 60 50 Agricultural Worker(Million)

40

Non-Agricultural Worker(Million)

30 20 10

0 5 9 1

0 4 9 1

0 3 9 1

0 2 9 1

0 9 1

0 9 1

0 9 8 1

0 8 1

0 7 8 1

0 6 8 1

0

3)Multiple bar diagram

In multiple bar diagram two or more sets of interrelated data are represented.

For Example:- The total proceeds and total costs (in thousand of rupees)of a firm for the years 2000-20005 may be represented by a multiple bar diagram.

The total proceeds and total costs (in thousand of rupees) of a firm for the years 2000-20005 Year

Total Proceeds

Total Costs

2000

22.0

19.5

2001

27.3

21.7

2002

28.2

30.0

2003

30.3

25.6

2004

32.7

26.1

2005

33.3

34.2

4)Percentage bar diagram

The length of the bars is kept equal to 100 and segments are cut in bars to present the components (percentage) of an aggregate.

For Example:-The actual outlay for the public sector in India’ first two Five-year Plans under different heads of development expenditure may be represented by a percentage bar diagram.

Development expenditure in different sectors in India’s first two Five-year Plans Head of Development

Percentage of Total Outlay Plan I

Plan II

Agriculture and Community Development

14.8

11.7

Irrigation and Power

29.7

18.9

Industry

5.0

24.1

Transport and communications

26.4

27.0

Social Service

21.0

16.5

Miscellaneous

3.1

1.8

Total

100.0

100.0

120 100 80 60 40

3.1 21

26.4 5

1.8 16.5 27

24.1

29.7 18.9

20 0

14.8

11.7

Plan I

Plan II

Agriculture Irrigation Industry Transport Social Service Miscellaneous

5) Deviation bar diagram

Deviation bars are popularly used for representing net quantities-excess or dificit,i.e,net profit ,net loss, net import or export,etc. Such bars can have both positive and negative values. Positives values are shown above the base line and negative values below it.

Pie Diagram

Pie diagram is a circle whose area is divided proportionately among the different components by straight line drawn from the centre to the circumference of the circle.

When the statistical data are given for a number of categories or and we are interested in the comparison of the various categories, such a diagram is helpful in effectively displaying the data.

For Example:- The entire circle or pie, may represent the budget of a family for a month i.e. Rs.7000/- and the sections may represent portions of the budget allotted to food,rent,education,savings and miscellaneous, as shown in the below table. Item

Amount (Rs)

Percentage of total budget

Food

3150

45%

Rent

770

11%

Education

1400

20%

Savings

980

14%

Miscellaneous

700

10%

Total Budget

7000

100

For drawing a pie diagram, it is necessary to express the value of each category as a percentage of the total.

Since the full angle 360 degree around the centre of the circle represents the whole budget i.e. 100%, the percentage figure of each component is multiplied by 3.6 degree to find the angle of the corresponding sector at the centre of the circle. 100 ---------------------------- 360 degree 1 ---------------------------- 360/100 =3.6 degree 45 ----------------------------- =3.6 x 45 = 162 degree

By this way, we can find out the angles corresponding to each sections, Item

Amount (Rs)

Percentage of total budget

Food

3150

45%

Rent

770

11%

Education

1400

20%

Savings

980

14%

Miscellaneous

700

10%

Total Budget

7000

100

Angle(degree) 45 x 3.6 = 162 11 x 3.6 = 39.6 20 x 3.6 = 72 14 x 3.6 = 50.4 10 x 3.6 =36 360

Line Diagram

This is the most common method of representing statistical sata,especially used in business and commerce, where data are shown in accordance with the time of occurrence. The line diagram shown by means of a curve or a straight line, the relationship between two variables. Two straight line, one horizontal and the other vertical (known as X-axis and Y-axis respectively),are drawn on a graph paper, which intersect at a point called origin. The given data are presented as points on the graph paper. The position of any point is determined by the distances from the axes on the basis of any given data. The consecutive points thus obtained are joined by pieces of straight line, giving the line diagram.

Year

Number of worker(Million)

1860

10.5

1870

13.0

1880

17.4

1890

23.3

1900

29.1

1910

37.0

1920

42.4

1930

48.9

1940

51.7

1950

59

Table 1 :- Total number of worker in India (1860-1950)

Chart Title 70 60 50

tle T is x A

40 30 20 10 0