Basic Experimental Designs
Statistical tolls or techniques are used to extract information, which otherwise remain hidden, from a set of data. As has been mentioned earlier, data can be gathered/collected from existing population (through sample survey technique/census method) or can be collected by conducting experiment as per the objective of the experimenter. In the first case, the researcher has little choice of controlling the external factors while collecting information from the existing population; the maximum the researcher can do is to orient the collected data from a befitting sample so as to explain the objective in mind. This type of data collection is mostly used in social, economical, political, and other fields. On the other hand, in the second option, the researcher has greater control over the data to be collected for specific purpose through experimentation. The researchers can exercise control to the extraneous factors to some extent allowing the desirable factors to vary. To examine the performance of different varieties of paddy with respect to yield, the experimenter can select the varieties as per the objective of the program and put all the varieties essentially under the same protocol so that only the source of variation can be the varieties. In this chapter we are concerned about such experimental procedure, collection of data and their analyses toward meaningful inference about the objectives the experimenter has in mind.