ABSTRACT
Researchers collect data from their experiments in a systematic, scien tific way in the order in which they occur. The data they collect are primary data, and usually bulky in nature as they consist of many observations. These data are called raw data or ungrouped data or unclassified data. These data are only a sample from a population of observations. The population may be of any size. Using the sample, we estimate the population values. An important characteristic of the data is variation. Variation is common in a myriad of characteristics. Some characteristics that show variation are: age, sex, height, weight, crop yields, blood pressure, blood sugar, tempera ture, sale of commodities, rainfall, wages of agricultural laborers, number of employees in supermarkets, soil fertility, amount of sunshine, etc. One cannot make any inference or conclusion as the values of the mass of data and the degree of variation show variation from one datum to the other, and the degree of variation varies from character to character.
