In the singular sense, statistics refers to the methods and principles of (i). Collection of data (ii). Presentation of data. (iii). Analysis of data, and (iv). Interpretation of data.
(i) Collection of data :
Collection of data forms the beginning of any statistical stud or enquiry. At the outset a researcher identifies the problem and then he collects data on that problem. He can collect the data in two ways. First, data can be collected from the original source. Such information are called ‘primary data’. Second, he can also gather the same information from some secondary source. These are called ‘secondary data.’
(ii) Presentation of data :
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Data which are collected by the researcher from the primary source for the first time are Raw data. Raw data are like raw materials. As such they do not convey any meaning. So after collection, information should be organized and presented properly. Presentation of data is essential for their analysis Generally, data are presented in terms of tables or by using graphs or diagrams. That gives tabular, graphs or diagrammatic presentation of data.
(iii) Analysis of data :
Valid conclusions are derived by carefully analyzing the data. For analysis data must be arranged in groups or classes according to some similarities or resemblances. This is known as ‘classification of data’. Classification makes the analysis simple and intelligible. For this, it is said, “classification and arranged facts speak for themselves. Unarranged, they are as dead as mutton”.
(iv) Interpretation of data :
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The final step in a statistical enquiry is the interpretation of data. Hence the results of the enquiry are examined carefully to draw conclusions. The interpretation of data depends on the intelligence and skill of the statistician. He must be very careful while deriving conclusions. The conclusions derived from an enquiry entirely depends on common sense and proper interpretation of data. Correct interpretation gives valid conclusions, otherwise the result may be very much confusing and misleading. This may cause ‘distrust of statistics’. As an example, suppose that the number of accidents are less in foggy weather than in clear weather. If it means it is safe to drive in fog, the result becomes misleading. It has been rightly pointed out “statistics are like clay out of which you can make a ‘God’ or a ‘Devil’ as you please.”
Thus statistics can be used either in plural or in singular sense. In plural sense it means quantitative facts or numerical data. In singular sense it refers to statistical methods or techniques used for making wise decisions in the face of uncertainty.