The following guidelines need to be observed for diagrammatic representation of data:

(i) **Selection of proper diagram: **Since there are different types of diagrams, it is inordinately necessary to select the proper type of diagrams, most appropriate, and suitable for the data under study. If the diagram selected is not fit, and proper for the data it will give rise to confusion, and distorted impression on the part of the observer. Hence, extreme care should be taken in selecting the proper type of diagram.

(ii) **Simplicity: **The very purpose of resorting to diagrammatic representation of data is to eliminate complexity of data, and make them easily and readily understandable by a man of ordinary prudence. As such, the diagrams should be drawn in as simple manner as possible. For this, too much of information should not be loaded in a single diagram. If the data are of multitudinous character, two or more diagrams may be drawn each presenting some identified characteristics of the data.

(iii) **Attractiveness. **One of the chief objectives of diagrams is that it should look attractive and imposing. For this purpose, the diagram should be drawn in absolutely neat and clean manner. If, necessary, they may be decorated with proper colours, shades, and artistic letters.

(iv) **Heading: **The diagram should be headed properly at the outset which would clearly convey the pith and substance of the subject matter under review. For this, an appropriate title of the diagram should be given at its top preferably with the words “Diagrammatic Representation of data relating to….”. Such a title may also be given at the bottom of a diagram.

(v) **Size: **The size of the diagram should neither be too big nor too small. If it is too big, it may look ugly and inelegant, and it may not be possible to accommodate all the data in a standard size paper. If it is too small, it also may look indecent, and inadequate, and it may not present the characteristics of the data in a prominent manner. Thus, keeping in view the size of the paper, the number of diagrams to be drawn and the characteristics of the data to be depicted, the size of each diagram should be carefully fixed.

(vi) **Proportion of length and breadth: **Through there is n such hard and fast rule in regard to the proportion of both length and breadth of a diagram. According to Lutz, they should be in proportion of : i.e. 1.414 to 1. This means that the longer side (vertical or horizontal) should be 1.414 times of the shorter side (vertical or horizontal) of the diagram. If the proportion of the length and breadth the diagram is maintained in the above manner, the diagram looks attractive, decent, and impressive else, it may look ugly and confusing.

(Vii) **Scaling: **Proper scaling of a diagram is very important for representation of the data and for deriving conclusion through them. Basically, there are two axes viz. horizontal and vertical, of a diagram which are to be scaled properly. Further there are two types of scale viz., Natural scale, and Ration scale (Logarithmic scale). In natural scale, equal distance represents equal value, and such a scaled proceeds in the manner of arithmetic progression viz. 1,2,3,4,5, etc., or in mumtiples of some even or odd number viz., 0,2,4,6, etc., or 0,5,10,15 etc. In ration or logarithmic scale, equal distance does not represent equal value but equal proportion of value. Such a scale never starts with 0 but from 1 and proceeds at a geometric rate viz. 1,2.4,8,16,32 etc. or 1,10,100,1000,10000 and so on. It, also, can proceed with the logarithms of the given numbers with equal divisions. However, it should be remembered that the horizontal axis is always divided according to the natural scale, and the vertical axis may be divided either according to the natural scale, or according to the ratio, or logarithmic scale.

Further, it is not necessary that equal distance should represent equal values in both the axes, even if, they are divided according to the natural scale. The vertical axis may be divided in multiples of 5 or 10 while the horizontal axis in multiples of some odd or even number viz. 0-1-2-3 or 2-4-6 and so on.

Further, it is not necessary that equal distance should represent equal values in both the axes, even if, they are divided according to the natural scale. The vertical axis may be divided in multiples of 5 or 10 while the horizontal axis in multiples of some odd or even number viz. 0-1-2-3 or 2-4-6 and so on.

However, the scale of both the axes should signify clearly and briefly the description and size of the units they represent viz. “thousands of rupees”. “units of production in millions”, “hundreds of persons”. etc. Moreover, all the letterings should be made easily readable without turning the paper up and down.

(viii) **Note of reference: **For ready reference and comparative study, it is required that each of the diagrams should be assigned a number or an alphabet letter.

(ix) **Note of source: **For proving the veracity of the information represented through a diagram, a note should be made of the source from which the data have been obtained. This will augment the authenticity, and reliability of the information to the satisfaction of the learned observes, and research scholars. Such a note should be appended at the bottom of the diagram.

(X) **Foot note: **For clarifying certain ambiguities, some notes should be added at the foot of the diagram. For instance, if a particular year is a financial year, and all the rest are calendar years, it should be mentioned in the foot note in order that any confusion that may arise in the mind of an observe is done away.

(Xi) **Index: **Lastly, an index of the colours, shades, lines and designs used in the construction of the diagram should be given briefly in order that the observed can easily make out the significance of the diagram.