Page 61 - DCOM203_DMGT204_QUANTITATIVE_TECHNIQUES_I

Quantitative Techniques – I

Notes 4.1.3 General Rules for Making Diagrams

A diagrammatic presentation is a simple and effective method of presenting the information
contained in statistical data. The construction of a diagram is an art, which can be acquired only
through practice. However, the following rules should be observed, in their construction, to
make them more effective and useful.

1. Appropriate title and footnote: Every diagram must have a suitable title written at its top.
The title should be able to convey the subject matter in brief and unambiguous manner.
The details about the title, if necessary, should be provided below the diagram in the form
of a footnote.
2. Attractive presentation: A diagram should be constructed in such a way that it has an
immediate impact on the viewer. It should be neatly drawn and an appropriate proportion
should be maintained between its length and breadth. The size of the diagram should
neither be too big nor too small. Different aspects of the problem may be emphasised by
using various shades or colours.
3. Accuracy: Diagrams should be drawn accurately by using proper scales of measurements.
Accuracy should not be compromised to attractiveness.
4. Selection of an appropriate diagram: There are various types of geometrical figures and
pictures which can be used to present statistical data.
5. Index: When a diagram depicts various characteristics distinguished by various shades
and colours, an index explaining these should be given for clear identification and
understanding.
6. Source-Note: As in case of tabular presentation, the source of data must also be indicated
if the data have been acquired from some secondary source.
7. Simplicity: As far as possible, the constructed diagram should be simple so that even a
layman can understand it without any difficulty

4.1.4 Choice of a Suitable Diagram

Diagrammatic presentation of data can be done in various ways. The choice of a suitable diagram
is a practical problem and should be done in the light of the following considerations:
1. The nature of data

2. Purpose of the diagram
3. The calibre of the persons to whom the information is to be communicated.
The choice of a suitable diagram depends upon the nature of the given data. It may be recalled
that two or three-dimensional diagrams are more appropriate if there are large variations in the
magnitudes of observations. Many a times, the purpose of drawing a diagram may also give a
clue to its choice. For example, if it is desired to indicate the comparison of values relating to
different situations, bar diagrams will be most suitable. Further, if one wishes to indicate various
components of a characteristics, sub-divided bar diagrams can be used. The relative importance
of various components can be shown by using percentage sub-divided bar diagram. When the
number of components become very large, i.e., more than three or four, circular diagrams are
preferred because bar diagrams look more crowded. If the statistical data consists of a series of
observations with different components for each observation, percentage sub-divided bar
diagrams are more suitable than the circular diagrams.

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